I'm at 52% and that's fine for me.
If I beat people easily and can tell they don't have a very deep understanding of the game (I repeatedly punish obvious rolls and they keep doing them etc) then I leave immediately. If I play someone who is obviously better than me or plays a certain character well I play them for as long as I can to get better or practice the match-up.
Played a good Mega-man the other day, best one I've faced. Lost to him about 8 times with Wario, started out being 2 stocked, then gradually getting more competitive before I managed to win two in a row, he switched to Pikachu and the process began again, losing a few games then getting an idea how to handle a decent Pika.
This leads me to having lots of one-off wins against sub-par opponents then losing 15/20 games against a good player in close games. I really prefer losing a close fun game to winning over someone who just rolls and smashes with no subtlety.