I regret that I don't practice my piano much, maybe a couple of hours each week. I'm primarily a guitarist, but I've been playing the piano now for about 18 years, but more like the first two years repeated nine times :),
I love the piano, if I could ever get a hit song such that I don't have to do much else for a living, I would practice all day long. But, I can play fairly well, and if I had 50 songs memorized, I could probably hold a gig as ambient music in a restaurant, but don't ask me for a tune I don't know ! I suppose the reason that, after all these years, I don't have much memorized is that I use the piano mostly for writing, not performing or learning other's songs. I'm 60 years of age, and I started in my early 40s, so a word to elder folks, if you want to start, it's never too late, and I'm proof of that.