Having made a creditable attempt at Mozart's "Rondo Alla Turca" (the last part of Sonata XVI, K300i) some years ago, I thought I should try to learn the rest of it. It's slow going. Then it occurred to me that if people can learn French by playing French tapes while they sleep, then I could learn the rest of this sonata by playing it while I sleep.
I've tried this for a month now. I can't say that I play Sonata XVI any better, but I can identify all of my mistakes with perfect accuracy.
To be fair to myself, Mozart did cram a lot of notes into some very small spaces. If I get daring, I will attempt his Fantasia (K475). In measure 84, he wishes the player's right hand to strike the keys 49 separate times (ignoring doubled notes), and in measure 85, he inserts 40 grace notes between the end of the second beat and the start of the third beat. Moussorgsky and his 11 fingers aren't looking so bad.