For myself, I like a healthy mix, but not too much kanji at once. I’ll usually do a couple of sessions of only last level’s vocab… but interspersed with that a mixed bag session with 1-2 radicals and 1-2 kanji and the remaining 1-3 items as vocab (I have my lessons on the default batch of 5). So two separate sessions of 5 will equal 10 items for me… 5 old vocab, and some mixture (as stated above). But I’m not trying to level quickly… I’m trying to do what’s easier for me. I’ve discovered I’m pretty terrible at remembering kanji if I try to learn too many at any one time. Vocabulary is easier, because it’s building on the kanji I already know.
If you use the Reorder script to get all your radicals and kanji done right out of the gate so you can level up faster, just make sure to not leave your vocabulary behind. In the 2-3 days left before you level up, you can work on the remaining vocab (if you’re aiming for the quickest 7 day levels).
I’m totally a “Take it slow” person, though… so you’ll probably want more advice from someone on the Gotta Go Fast team.


