I do decently on radicals and some of the most obvious vocabulary, but I would often get kanji and some vocabulary wrong several times before it started to stick. It wasn’t really affecting my level up speed (I do 10 lessons a day, except for radicals, which I do in one batch, and since I started doing this, I’ve never run out of lessons to do), but I did start to worry that I would mess up and end up with a couple days where I had no new lessons, so I downloaded the self-study quiz userscript, and now I test myself with that after every batch of new lessons. It turned out to be just what I needed to actually learn the kanji after the first lesson instead of failing them several times before the meaning/reading starts to stick for me. It doesn’t take much time to run through the quiz a couple times after doing my lessons, and it massively benefits my learning to do so.