I know the OP was regarding HS players, and pitch counts (I think), however this is somewhat relevant.
Was watching MLB Tonight, and the conversation came up with the new obsession with setting up an innings limit for young pitchers with big contracts. They were discussing whether St. Louis was going to have a limit on innings for Wacha, same as they did for Strasburg, and were going to do for Harvey, prior to his injury.
Ron Darling indicated that GM's and Owner's were cautious with young big arms that are attached to big contracts (or will be soon). Darling mentioned, "these young men were abused by overuse by coaches at the youth, high school, and college levels, and so they come up to the "bigs" with mileage on their arms". I found that statement interesting, although I know it was an over generalization.
I also remember hearing about a camp / clinic that either Dr. Andrews or Dr. Jobe gave where MLB had him lecture on proper protocols regarding limiting injuries to pitchers. Innings, pitch counts (overuse in general), along with mechanics, etc., were used as general guidelines on how to "reduce" arm injuries. At the end of the clinic, he left with this parting statement (paraphrased) - "even with all of the topics covered over the past few days, and adhering to every one of them, the truth of the matter is the medical community just DOESN'T know how to prevent arm injuries in pitchers".
I have heard it mentioned before, and I don't know if I believe it, however there is a train of thought out there that subscribes to the notion, that a pitcher, regardless of perfect mechanics, not being overused, etc., has a specific number of "bullets" (pitches) prior to some type of physical failure / injury. Each pitcher is different in how many "bullets" they have. Now I am not saying you don't increase, or decrease odds with a common sense approach, but the truth is not many understand the real cause of injury as it relates to a very unnatural motion for throwing a baseball overhand in a very violent manner.
I get emails daily from a pitching "guru", that markets his pitching program online as the one, and only program based on proven "science". While I agree with him on a lot of what he says, and I even flew Jr. out to his neck of the woods to work with him in the past, he landed with egg on his face. As soon as Matt Harvey took MLB by storm last season, he was using him as a poster child as an example of the mechanics he taught. Every day he referenced Harvey in one way or another......then Harvey got hurt. The silence was deafening regarding Harvey....likely he was taking time to think on how he was going to react to the injury, after he was telling everyone that Harvey's mechanics was the gateway to throwing hard, injury free, with proper mechanics. This "guru" all of a sudden came up with, "I found the one component of his mechanics that is the cause of the UCL strain, and "nobody else would have caught this but me". Funny, how his mechanics prior to the strain were flawless, but all of a sudden, he knew exactly why he was injured. His reasoning, was because he "long arms" the ball, which is "what ONLY traditional, non-informed pitching coaches teach".
Anyway, just wanted to throw in some information that relates to high pitch counts. Yes, I stand firm that high pitch counts at the youth level are not a good thing. I don't know whether HS coaches knowlingly put kids in a dangerous situation, I suspect a few do, however I also respect the many that are well informed, under paid, and often criticized. Many don't realize that "in the day" 150 pitches was nothing for a starting pitcher, and guys like Gibson used to do it all the time. In fact, some folks are wondering if the injuries occurring today are a result of "underuse". The body will (for the most part) be able to accomplish just about anything it trains itself for. With such strict adherence to pitch counts, inning limitations, mandatory "no throw" periods, we certainly are not training for heavy loads. It is possible that is also part of it.