I don't think it's the lack of direct shoulder work that's the problem (in regards to Bench Press oriented injuries). It's the lack of pulling movements that's the problem. You'll see 100 sets of pushing movements, but only 20 sets of pulling movements in most gyms these days, and most of the pulls are at the cable machine. I remember clearly there was this young man who wanted to push up bigger weight in his Bench Press, so these meatheads where showing him board presses which was fine and good, but they didn't pay any attention to his winged scapulae, lack of back muscles, and his lack of tricep mass. To top it off he was complaining about his shoulder.