I remember thinking, when I had played the harp for ten years, how well I could play. I really had mastered the instrument. When I had played the harp for twenty years, I remember thinking, how well I could play. I had really mastered the instrument. The same thing happened after three decades. Now, after four decades plus, I REALLY HAVE MASTERED THE INSTRUMENT AND REALLY KNOW HOW TO PLAY! Guess what I’ll be saying at fifty years, I hope.
P.S., It’s exactly the same with pieces you learn. You’ll really know them after 20-30-60 years.