Hi virtuosos and on-their-way-to-be-virtuosos, (this is my first post)
it took me 2 hours to memorize Op. 10 No. 2, yet it took me 7 hours a day for 5 days, to memorize the middle section of Op. 10 No. 3, I memorized Op. 10 No. 9 within an hour, but got my brain fried trying to take down The black key etude.
And also, are etudes more difficult to memorize than other piano music of the same level, say Chopin's Prelude No. 24 or Flight of the Bumblebee...
Recently I accepted a challenge to learn the first cadenza from Prokofiev's Second Concerto, and I feel it's a lot easier to memorize than Winter Wind...