Can't really comment on number of pieces, since the pieces in my repertoire vary between about 20 seconds (the song 'I am Rose' by Ned Rorem is, IIRC, the shortest I've played) and over 4 hours (some of Wagner's operas), but at a very rough estimate my average, since I began playing the piano all those years ago, is about 10 hours of new repertoire a year. Now that my repertoire is the size it is, the rate of learning new pieces is naturally declining because I more often get asked to play things I've done before.
As I've said before on this forum, accompanists have the most fun!