At first I was doing way more reviews than now (though I can’t remember how many exactly), but that’s because I had studied N5 and N4 grammar elsewhere, so it was easy to do lots of grammar points a day.
I think it took me around 6 months to do N3. Then, when I hit N2, I slowed way down. I picked up the pace towards the end of last year, but it took almost a whole year to finish N2 lol. Now I’m at a normal pace, doing a couple of N1 reviews per day. However, I’m almost done with N1 (got like 2 or 3 days left).