im a week in, and i’m currently level 2. I’ve done about 600 reviews this week at 95% accuracy, or about 85/day.
i also do 1-3 hours of studying w my genki 1 textbook.
is this too fast/counterproductive? my goal is n3/n2 by next summer.
I think the only one who can answer this – is you.
Everyone is different and has their own pace.
If at some point you would start feeling overwhelmed – then it would be a good indication that you might want to slow down. If not – then there is nothing wrong with going at your current speed!
It’s not that you have to slow down – it’s that you need to remember that it’s ok to slow down if you would feel like you need it!
In any case, best of luck with your studies! 
Only you knows how fast is too fast, keep an eye on your review load. If it gets overwhelming, stop doing lessons but always do your reviews until it calms down.
I found that focusing on kanji early on is worth it, it boosts your reading comprehension massively.
I don’t see how it could be counterproductive, unless you burn out. I recommend carving out a “bare minimum” routine that you commit to doing every day, and then you can do more as a bonus if you want. I find it motivating and makes it easier to stick with it long term.
For instance it could be “do all my Wanikani reviews and 5 lessons”. If you’ve done this then you can tick off your Japanese for the day, or do more if you feel like it.
You’re always super motivated when you start a new language, everything is new and fresh and you progress very quickly. Eventually you’re going to have a bad day where you don’t feel like doing 4h of Japanese. You need to be ready for that and make sure it won’t derail you.
Do you mean that you want to pass the tests or you’re just giving a rough estimate of where you want to be fluency-wise?
N2 in a year is technically doable but is going to be hardcore. N3 is more reasonable but will still require very strong discipline. Goal setting can be useful, but I find that I personally prefer to focus on the journey and keep my head down. I arrive when I arrive.
I do want to pass the test, N3 would be good but N2 would be even better. I’m doing this so I’m a better candidate for a japanese government scholarship. (And so I can consume more japanese media, obviously)
you will know when its too fast. some weeks are better than the others and some are worse… if you start to see too many incorrect reviews or if your accuracy in either reading or meaning drop drastically on a given day compared to your baseline, its time to slow down… if your goal is retention and not running through the levels that is…
I second simias here. Technically possible but aiming for N2 in this time frame is faster than what you get in full time language school in Japan. It’s not impossible since the schools try to give you a more well roundedness with speaking and writing being included, but it IS a full time job.
If you have something else going on I wouldn’t aim for N2.
Otherwise as others have said, as long as you can keep doing something and don’t stop completely because you feel overwhelmed, go as fast as you want.
Try to tune your senses (and actually stop adding lessons) to feel when it starts getting overwhelming before you stop compeletely because of burnout and you should be fine.
I think too fast is when Wanikani or SRS is taking up too much time that you can’t up as much time into the other aspects of learning as you want. Early on the kanji and vocab are pretty common so you get alot of value at first, later on you get more value out of an hour of immersion than an hour of Wanikani in my opinion. Also, be wary the review volume will increase a bit once Enlightened items start to become Burned.