a simple task on a weekly basis

It's sort of funny, in a way, that he is known for piano études, because he doesn't even consider himself a piano player, really, but there it is. I think it went this way: he wrote an étude (by which I mean a short piece that focuses on a particular skill among the generalized skills putatively required for good piano playing, in order to hone this particular bit of muscle memory, or perhaps, more simply, a piece that has a monomaniacal skill-oriented focus) for a friend, enjoyed it, and...