As someone who did speedrun N5-N3 over maybe 3-5 months I ended up needing to reset as my grasp of everything was quite weak, even with a reasonable retention rate when doing reviews. I moved to Japan around when I finished N3 and realised that I couldn’t truly understand the grammar which I had learnt and thought that I “understood”, let alone use it. I think resetting wasn’t strictly necessary and if I hadn’t moved to Japan and I had remained in the safe bubble of at home self study then I also wouldn’t have noticed my weaknesses quite as much and they would have just been fixed over time. I gradually re-added N5-N3 (like 3 new a day or something which was reasonable as I had already studied it all) and then after that only “mined” grammar that I had already seen used or looked up.
I was also spending a fair chunk of time doing SRS at that early speedrun stage as well which I now would probably advise against. It feels extremely productive when you are a beginner since you feel like you are learning a lot (and just proportionally to what you already know you techinically are) but very often the only thing people are speedrunning is the SRS itself and not actually Japanese.
So likely it comes down to personal goals, expectations, etc. That ignores the very obvious question of how much time people spend studying each day which has a very large influence, clearly, but I would still advise those with a lot of time to study to still limit their SRS time to 30ish minutes and then spend the rest getting input or, for complete beginners, doing a textbook or reading a grammar guide or graded reader or something.
Basically, don’t feel bad - your Japanese is probably quite strong in some areas where speedrunners are weak. The achievements of speedrunners are impressive and some stand out as having achieved seriously impressive things but having been learning Japanese for a couple of years at a fast-but-still-sub-speedrunner pace and having watched online Japanese learning spaces that whole time I see more speedrunners come and go in a shining ball of burnout than I do see them actually get good. Very very few people get good to begin with (N1 is not “good” in this definition - I mean actually good) and full speedrunning isn’t sustainable for a long time, I mean years not months, if you have a life. As I am always saying on this forum, the main thing is to just keep pushing and not stop. The ones who make it are the ones who don’t quit.