I bought 90, but in hindsight I should have bought a 30 day subscription. I took about 30-40 pages of notes for both OC and GC. If you still need practice after the videos expire in 30 days, just subscribe to his quizzes.
I bought 90 and, like customx, took very detailed notes. His quizzes are great. I just finished re-watching them all on 1.5x speed (which is nice) as review for my test on Thursday.