Originally Posted by Doubles
Hitting flat doesn't break poly. Hitting with spin does. If you've played with poly for 20 hours, whether it's match play or practice, and you still haven't broken it, then you don't have the swing speed to fully utilize it.
In my experience, poly breaks more from stretching than sawing, but whatever.
I was unaware that practicing volleys and rallying doubles put a lot of wear and tear on your strings.
But seriously, step off of your medium height e-coaching horse.