Super familiar with both Zach and the Jammer. We used the entire lineup while I was at Nebraska. I do think traditional S&C gets it wrong quite a bit when using mainly barbell exercises. Super easy to further the imbalances if you're pushing a barbell on the bench press or squatting/deadlifting because a weakness in one area can be overcompensated by a stronger area. We did, and I still do, a lot of single arm/single leg exercises. The best explanation I've heard of this was by a former Assistant of ours Chad Beckman, who would ask you if your body was symmetrical or asymmetrical. If your left side isn't exactly like your right side, why would you train them as such? Really hit home and made you understand that while the core movements and barbells weren't bad, there were auxiliary movements and other things that we should be doing as well to insure total body strength and more importantly, injury prevention.This would help as far as getting more full-body workouts, but it's the nature of lifts like the bench-press that cause the problem, not just that they're doing it too much. Again, this is by far my weakest area as a coach, so throw out anything that I'm saying that conflicts with whatever @ShortSideOption says because he clearly knows his stuff when it comes to S&C.
The problem isn't just that they're doing too many/too much bench, it's that they're not doing the reciprocal strength work to build up the opposing muscles and counter-acting the strain on the ligaments, cartilage, and smaller muscles. Have you seen the jammer? It's a stand-up push-pull machine that has one arm pushing while the other is pulling so that there is resistance both ways. (Fwiw, I'm just repeating what Duval said on Saturday morning.) If there isn't the pulling component, the stress created by the muscles building up in only one aspect creates a strain (No Diaco jokes, please!) on the tissues and surfaces where the stronger muscle is not pulling.
This part is me talking, so it's probably wrong, but the way that I visualized it and explained it to other coaches who didn't hear the talk is that it's like you're overloading one side of a teeter-totter by overworking one muscle while ignoring the other side. The difference in the analogy, though, is that an overweighted teeter-totter would just stay stationary, whereas with the muscles, the firing of the developed muscle will tear something somewhere, eventually, if it is countered.
Now you can wait for someone else to correct what I said.
I just don't know that it's reasonable to ask high school coaches to get their CSCS, or gain the knowledge given the time constraint a lot of them have and the lack of pay in a lot of instances.