I pitched from the time I was 8 until 17 and just ruined my arm. There was a ton of pressure to keep throwing that I wouldn’t tell the coaches when my arm hurt.
I can't stand coaches like that. Coaches should be emphasizing arm-preserving mechanics in those age ranges - not pushing for wins at any cost.
I learned the hard way one day: Never, ever, ever fake throwing a pitch without curling your fingertips as if around a baseball. I think it was the blood flying within my fingertips, but Oh My God that hurt.