I think I have listened to that youtube video of Valentina Lisitsa playing the Moonlight Sonata half a dozen times or more since he posted this article. What a great composition and a masterful performance.
That and Rondo a Capriccio. Of course the others are all good too, but it's much easier to commit to 6 or 14 minutes of listening than 60. ; -)
That's the thing about music, isn't it? Listening to any performance takes time. There's no equivalent to "speed reading" or "skimming," either. Well, I suppose you can drag the playback slider around looking for the good bits, but it destroys the experience.
As I'm sure @cmp2020 has realized by now, learning a 20 minute piece means playing through that piece hundreds of times. That's a lot of hours! No wonder it takes so long to build up a decent repertoire.