Good Point Chris.
I would not want anyone picking up a shot and heaving it. I used the Worth Weighted Ball Set. The heaviest ball I used was 7oz. I followed the program Worth provided with the balls, but only completed 75% of it before winter. During practice, I would throw with the 6oz ball for 10-12 minutes before using the regular ball.
I would also add that now, at 29 years old, I have never had any problems with my arm since the labrum operation. I have been throwing BP for the last six years during the spring and summer. I bet I throw 50-75 BP pitches a day for six months and I have not missed a day throwing in all those seasons.