We’d all like to skip to the part where we’re awesome.
We all enjoy the feeling of competence. It’s much more fun to play an old piece than it is to learn a new one. Thus, it’s tempting to use our rehearsal time on things we are already good at.
But if you want to grow–you have to courageously identify and do focused practice on the parts you’re not good at. Not as much fun–but a much bigger payoff in the long run.
Of course, I’m not just talking about music–any new skill you want to acquire requires this courageous step toward the tricky spots and drilling your way to mastery.