I think the keyword here is PATIENCE.
Chopin etudes are demanding stuff. Demanding stuff takes, believe it or not, time. Don't rush the learning process, let each stage sink in.
From my (albeit limited) chopet experience, slow practice - or, more precisely, slow-motion practice - is indeed a key component. Every single note counts, and there's certainly a damn lot of them in chopets. And they occur in weird places. Patience. And thoroughness, every little detail thought out, every single motion made knowingly and economically, no extra motions, etc., etc., just about like every other hard piece.
My two cents.