I’m curious, especially about the people who have learned Japanese for a long time.
What sort of content are you interested in, and at what point did it become comprehensible without stops to look things up?
I’m being vague on “at what point” because I’m not sure whether to ask “after how much time”, “at what N level”, “after how much vocab”. 
Not like I’m being impatient, it just feels like I’m still eternities away from it.
I am sure everyone has their own opinion on this, but I have been studying for about 1 year and a half now, probably spending a total of 2 to 3 hours a day either reading, watching, using websites like Bunpro or Wanikani, etc. I know some people swear by Anki, but I stopped using it myself.
I recently played a VN called Letters From a Rainy Day and I tried to play it in Japanese only, but I did switch it to English from time to time to check sentences. There were times where I could fully understand it, but then some points where I had no idea what they were saying. After finishing it I tried Wagamama High Spec, and it just completely lost me. It kind of frustrated me because I thought “How can I understand one thing, but not the other?” (Although I am aware it’s harder than Letters from a Rainy Day).
The thing that has helped me the most I would say would be learning Kanji, I would say I roughly know around 1000, so if I don’t know a word I can look it up, especially when there isn’t furigana. It just depends on how much effort you put into it I guess.
I am sure some people who have studied double the amount of time would maybe agree, or maybe disagree, but those are my thoughts. Just keep at it!
I’ve been studying for about 2 and a half years. I made it through N2 on Bunpro but decided to start from scratch before continuing to N1. Also around level 45 of Wanikani and spent 2 years in Japan.
I still feel pretty far from “native” fluency, but Id say near the end of N3 is when I could actually start having conversations with Japanese people and it not be completely painful. I still don’t have the best stamina for reading, but can usually get the gist of what’s going on without looking anything up. If its something easy like pokemon I feel like I have close to 100% understanding, but then I try to watch an episode of Gintama and only vaguely understand it lol.
The experience will be different for everyone so try not to compare yourself too much with others. And I recommend trying to watch/read native content without stopping earlier rather than later. I always think it’s crazy when people say they pause every few seconds when they watch anime to look up words. I can’t imagine that actually being sustainable.
For me, it was the entire 2 years I have been studying. Currently in the middle of N4 grammar and have around 1000 wanikani items “burnt” and around 1000 more in rotation. I am more of a slower learner.
Early on, it was only simple things of the things I am learning. And as I learned more, more things clicked in.
I have a natural talent for understanding contextual things, so I have been able to follow the content without knowing all the exact little bits.
The content I watch is typically anime but I watch a wide range of things, even within anime.
I’ve put in around 2-3 hours per day studying for 3 years (technically 4 but I didn’t study at all my first year of marriage). I passed N2 back in November. I only consume JP content (books, YouTube, video games) with the exception of some YouTube channels I like to watch with my wife.
This is going to be extremely anecdotal and everyone is different, but in terms of “clicking”, it never really happened. Maybe that’s why I study so much. There is always a palpable gap between my English and Japanese that I find frustrating. I can grasp and understand 80-90% of the content I consume. But once I step out of my sphere of what I’m used to consuming, that can drop off dramatically. I notice my comprehension slowly building over time. There is no magic, “aha” moment.
I’ve been to Japan 3 times since I started learning the language and it has been really fun watching how my Japanese has grown on each trip. This past time I didn’t use any English with Japanese people I talked to. Conversations with locals about life in their city and how things had changed were really rewarding. Although this weird thing happens where as you get better at understanding Japanese, you realize how bad your spoken Japanese is and you feel like you’re actually getting worse…
For me, I started actually finding value and enjoyment in native content post-N3/early N2 stage, which was probably after about 2 years of study. My tolerance for ambiguity may be much lower than others, but it was painful and probably unproductive to even attempt native content until I understand grammar/vocab up to ~N3 level. I tend to have a much different opinion than a lot of people, but up until that point, your grammar/vocab knowledge is just too limited and time would be better spent learning the fundamentals.
I passed N3 last summer so I’m probably N2 or close to N2. I can read novels aimed at Japanese middle school students at a pace of about a page every 5 minutes or so. I can play Gyakuten Saiban an understand like 80% of it, but occasionally a character will have strong dialect or say a complex word in katakana and I get completely lost since I’m more of a visual learner so I understand through Kanji better. And for manga it ranges, something like chainsaw man I can read like a whole volume in like 30 minutes to an hour but something like Hajime no Ippo is a bit harder so more like 2-3 hours. I still look up words that I don’t understand sometimes. So it really depends on what you’re trying to consume smoothly. If you want to watch anime aimed at middle school students I’d say N3-N2 is enough, if you want to read a book aimed at adults N1 and beyond. But really you never stop learning.
Some things are easier than others due to context giving lots of clues.
As for me games are by far the easiest to get into. Very simple to just follow the logic of the game and keep moving forward. Lots of people who don’t even know hiragana play Japanese games to completion. I suppose visual novel and adventure games would be tough, but something like the older 3D Zelda’s are really enjoyable to play even with basic Japanese. So I would say games are enjoyable even at N5, N4 level depending on the game. N3 level would get you through 90% of Japanese games.
Next would be manga. Lots of visuals to back up the dialogue. Some manga are more difficult than others or have aspects which are very tough. An interesting one is Berserk. Lots of action and a basic story that is easy to follow, but some really really difficult Japanese when it comes to world-building, lore and politics. Sometimes I wonder how they even manage to translate it into English. Personally, I found a well balanced manga to be Fist of the North Star. Dragon Ball (especially from where Z begins) is also good. I would say about N2 level to enjoy most manga without too much issue.
I’ll throw TV shows, anime and movies together, as I would say they are equally challenging. The dialogue is very compact and often doesn’t give any visual clues as to what is happening or what characters might be referring to. When it comes to anime there is lots of action sure, and chatty dialogue, but the moment they start talking about something that isn’t explicitly shown you really have to have some skill and a wide pool of knowledge to understand what they are talking about, especially if you’re not using subtitles. TV shows and films are the same. I would say N1 level at least.
Literature is a different beast for sure. Obviously you can “read” something on the surface, but the challenge with literature is to get to the point where you can understand, visualise or re-imagine what is happening or what the writing is expressing, in your own head. Obviously this is quite high level stuff and goes beyond just memorising words and grammar points. People who struggle with this in their native language are going to have an extremely hard time doing this in a second-language. So reading is by far and above the most challenging skill to get good at. That is not taking into account that Japanese literature encompasses a huge range of literary styles spanning decades. Skill level = ??? but realistically N1 minimum.
I’ll answer the question from my perspective first and then share where I’m at in my learning journey.
When does it click? It’s hard to say. Some days I feel like I have total understanding of everything I consume in Japanese and feel like a god, other days I’m completely overwhelmed and feel dejected. It really depends on the content/conversation. I am at a level where I can understand 80% of “every day life” type manga, dramas etc. More complex literature, specialised subjects etc. and that drops off significantly.
The main thing I’ve learnt is to be okay with those rollercoaster moments in the learning journey. Sometimes you’ll feel really good about your progress and sometimes you will wonder why the hell you’re bothering putting in all this effort because you’ll never understand this insanely complex language and it all sucks. I’ve learnt that small consistent progress adds up over time and it’s going to take years, decades, maybe even your entire life to master (if that’s your goal).
As for my learning experience. I’ve been “studying” Japanese since high school 18 years ago. I haven’t actively been studying for that long though.
I was probably N3 level until ~2.5 years ago when I really started taking it seriously. Since then my study has looked like:
It never will. Your doomed to forever be doing bunpro waiting for the day where it clicks. Just kidding (mostly). Unless your only immersion content is the highest level beautiful Japanese literature you probably won’t have a moment where it completely clicks. For example, I can read Horimiya in Japanese relatively easily, however if you told me to read a political novel I would look like I hadn’t even done Hiragana. So for consuming there’s not really a specific level where it clicks for everything.
HOWEVER. I would say that around N3ish is when you can start properly expressing yourself and thinking in Japanese. I feel around that level your issue is no longer “How the hell do I make a sentence” it becomes “How do I say baked beans in Japanese”. What I mean by this is that around N3 you can make sentences well enough, you just need more words to slot into your sentences.
Gonna pop in and mention something related and unrelated, that goes in line, but like, outside of the day to day stuff and that which got used a lot during school for studies, there is a shit ton of words that Japanese people dont know or can read. I asked a few friends of mine about why Japanese television is like that, with the Kanji all over the place and whatnot, and one of the answers was literally so the people wouldn’t mishear, or even to try to teach kanji. Because even if you grew up using it, some things can be forgotten, if its obscure and what have you.
If you were to show an N2 or even N1 jlpt test to your average Japanese person, they straight would be unable to do so. Or massively struggle. Speak to them about work and talking about specific vocab, they too need their electronic dictionary to make sure they use the proper kanji, proper tense within keigo ect. It gets kinda outta hand, even for the japanese.
So in line with what everyone else said, it’ll depend on what you consume and just that never ending using of the language. I think Kanji helps a lot too with general meanings, when you come across a word you dont know.
I did N1 25 years ago and tbh there’s always something to look up because the language is vast and it is forever changing! You can probably cover 90% of everyday conversation in a year or two though.
I’ve been studying for about six years, passed N2 two years ago and failed N1 once six months after I passed N2. To me, novels, drama and anime were relatively inaccessible until early N2, mostly due to a lack of kanji knowledge.
It never clicked. Once I understood some source material, I moved on to more difficult material. It is a never ending, gradual process. From beginner textbooks (N5) to NHK easy (N4/N3) to regular NHK articles (N3-N1), Wikipedia, novels, drama and anime. My level of understanding now greatly depends on my familiarity with the genre.
I like reading about natural disasters and crime on NHK, so those articles have become very easy. Topics that don’t interest me a lot, e.g. politics, remain somewhat difficult, mostly due to a lack of genre-specific vocabulary. I also like romance novels, drama and anime, so I find those a lot easier to understand than other genres. Moreover, in real life conversations I find women easier to understand compared to men. Probably because most language learning YT content is made by women and all of my teachers were women as well.
To absolutely no ones surprise, the more you practice a skill the better you get at it. That’s really all there is to it.
This is an interesting question, so I just thought I’d chime in from an “old-timer’s” perspective. 
At this point, almost thirty(!) years since I first began studying Japanese (with the past twenty of those spent living in Japan and using the language every day), I would say I feel like I’ve reached my initial goal, which was to reach the point where I could function in Japanese at a level approaching (if not equal to) an educated adult native speaker.
Was there one moment I can point back to where it all “clicked” and I was like…“Whoa, I know Japanese!” (I’m thinking Keanu Reeves as Neo in The Matrix here 
). Not really.
I remember having various “moments of enlightenment” along the way, like sitting down to talk to a Japanese friend after class and then realizing three hours later that we’d been talking in Japanese the whole time, or getting lost in a Haruki Murakami novel or a TV series and forgetting that I was reading/listening to a “foreign language”. But then, I also remember times after those moments when I would still struggle to read something, or get frustrated at not being able to express myself fluently or with my desired nuance, so while certain things might have felt breakthroughs at the time, often I still had a ways to go. (And of course, even now I’ll still pick up a new word or phrase from time to time – the learning process never truly ends.)
It’s not a straight path upward and forward, and it’s definitely not something that corresponds to a certain JLPT level or after learning X number of words, because rewiring your brain to process Japanese fluidly and fluently is a complex process involving a lot of interconnected factors, many of which often can’t be easily quantified.
As many others have said, too, the areas you improve at will also depend on what you spend the most time working at. I think at first it’s fine to stick with the things that interest you most (because you’ll be naturally motivated to want to understand them), but it also never hurts to step out of your comfort zone and challenge yourself to do something new. It’s kind of like exercise – you have to work out the various (mental) muscles to get the benefit.
At the end of the day, I think the most important thing is to develop for yourself an accurate sense of your own abilities, to know what your strengths and weaknesses are and make sure you’re working to fill in the gaps. As long as you’re doing that (and giving yourself consistent exposure to the language), you’ll find yourself understanding more and more over time, and while there might not be one moment where it all ‘clicks’, you will feel the pieces gradually fitting together, and your understanding and appreciation deepening over time.
If you ever feel like you’re stalling, you can always go back to something you read or listened to a while ago – many times, I think you’d be surprised at how much your comprehension has improved.
Best of luck in your studies!