My current bow draws about 68#at my 29" draw and is the only bow I practice and hunt with. I'm 6' 185#, 55 years old. I don't work out, though do work allot. If I lay off from shooting for a month or so it takes a few days of shooting to get back in shape. When in shape, I can easily shoot 50 + arrows in a day, never saw a reason to shoot much more than that.
Since I went to only shooting stick bows about 12 years ago I've had no shoulder problems. Watching the way some guys draw their compounds it's no wonder people have shoulder problems! Drawing your bow with your drawing hand down at your chest,than rolling your shoulder and raising your hand to anchor is a great way to invite problems.