I think at the beginning, a good coursebook is the best. Most teaches basic grammar, expressions, vocabulary and if followed consistently, one can gain useful knowledge within reasonable time.
I used minna no nihongo back in the day.
It is very hard to learn a language by learning grammar only. I go futher, it is almost impossible and tiresome. Without listening, vocabulary and output, speaking and writing, it is only one aspect of the langauge.
From my side I started to use bunpro to solidify grammar points with the view of doing the jlpt. If not for the jlpt, I would not use it becuase there are tons of different resources which would deliver what I need to reach my goals with less effort and more fun.
From my side,
I have one language class per week (45 min)
Use anki for words and kanji, becuase fsrs is much better than the srs bunpro offers (30 min daily but I lag behind, usually between sets when I am in the gym)
Do bunpro grammar, now 2 new items per day (this is doable)
Read Japanese daily, mainly light novels, will start news now (aim is 20 min)
Go to the local nomikai, held every week, if I can (this is my “night out”)
Have a chat with a language exchange partner once a week (60 minutes, we cannot always make it, but c’est la vie for working adults)
The Japan Foundation here has a Japanese talk event every month or so, I attend when I have the time (I will try to go more in the future, only they don’t have AC and summer can be brutal here)
Listen to podcasts (while walking, shopping, running)
All I watch is in Japanese, youtube, netflix (30-40 mins, when I have the time).
I work full time and except for the obvious events, like the nomikai on Friday, I squeeze things in whenever I can. Waiting for the bus? Anki. Grocery run? Podcast. Time between sets in the gym? Anki. Lunch time? Reading a bit. Lull in work? Anything.
I would need to add writing as output. This is where I struggle, for that, I simply do not have time left. I will need to review my schedule soon because of this. Maybe I need to spend less time on this forum to make time for writing.
Consistency adds up. Better to have a short amount of time dedicated well and consistently then trying to catch up with your 700 bunpro reviews in one day.
I would recommend considering a more balanced approach using different learning methods and approaches. Ask your choice of AI, give it your goals, your level, your current learning tools, the time you have daily/ weekly and it will give you a schedule. If you do not feel the progress, ask for another one, tweak it until it works.