Just curious: Having a not-insignificant level of sightreading yourself, how have you approached it so far? Did you let it develop naturally or try to improve it consciously?
Right now, my sight reading ability is limited to Chopin Fantasie-impromptu at about 70% speed with few mistakes, and that's an exception due to me hearing it many times. My actual sight-reading ability is limited to Henle level 5 or so.
I'm not aiming for John Ogdon level, sight reading Opus Clavicembalisticum with ease
I'd say I'm satisfied being able to sight read Henle level 7-8 pieces.
Issue is that I can't find any good sight-reading concepts online, and my new teacher is a self-proclaimed bad sightreader. Other than concepts like not looking at your hands, knowing the keyboard and such, how does one sightread at very high levels?