Or is it the other way around? Some days it does feel as though progress goes in reverse. At least I've done this enough to know that, like the market, you come out ahead if you hang around long enough. When I was younger, I would have tried to solve a passage such as the cadenza from my concerto by spending an hour on it, then throwing something at the wall! Now I'm more likely to do 5-minute chunks, 10 times in a day. And I like to remember that there are other passages that are not problems. Before I thought that was a weakness: to admit that there were sections that were going well. Now I know that it's healthy, and necessary, to acknowledge them. If you can't be honest about the things you like, you will never be honest about the things you don't. In both situations, you must be specific about what you hear: not just "this was good, that wasn't", but "I'm liking this passage because of x, this other passage sounds y."
Another two encores from Kissin tonight (both Chopin), and one of them I knew because it was a demo file either for a Yamaha keyboard or Finale music notation software!
"InstantEncore made launching a mobile app seem effortless."