About an hour I think, though spread out throughout the day. I do a maximum of 30 vocab lessons a day separated in three sessions of 10, sometimes slightly more if a session is radicals or the second half of kanjis needed for the level up =)
I have around 100-150 reviews on “next day” at all times, which is probably less than I do since I always have those new items of the day that gets repeated a few times. But would think about 200 reviews at best. Since I do the reviews in a timely mater they are all fresh in memory, or at the right spot according to srs, so I still remember them and they just fly by in a mater of very few minutes.
First time around I did bulk lessons of 100+, returning in just as huge bulks in reviews, ended up collecting dust in reviews before taken, and thus failed a lot of them , went slower and most returned in a few hours as they got bumped down. Had to reset from lvl 19. Doing bulks I ended up spending all day on it it felt like, got much less from it and generally learned very little. Doing a few at a time and always being on top of reviews means spending much less time and learning a whole lot more =)
. At my fourteen-days-per-level pace, it would be at the start of November, and I’m going “slow” by choice.