10 hours a day for the past 20 or so days is a recipe for burnout in spectacular fashion. Unless you're especially different from most people, I'd venture to guess the first 3-5 hours (for the first few days) were productive, while the last 5-7 you were probably burned out to the point where you were A) no longer learning anything B) actually regressing due to fatigue or C) so tired that you were learning things incorrectly, especially after 8 or 9 consecutive days of putting yourself through such mental abuse.
Go back to the drawing board and start over, budgeting around 2 hours per day on weekdays and 4-5 on weekends. And make sure you give yourself a day off every 2 weeks or so. Take an online class, like
MGMAT, if you want, and start working on a 2-3 month program to get your score up. It won't happen overnight, and at this point if you were expecting to apply R1 for this fall, it's probably a bridge too far.