I have found in my state over the past 40 years it is the high school teams that train the hardest simply do the best. These are teams that usually do 55mpw or more. I have noticed the training to be advanced and college like in volume. Long progression runs of 12 miles or more are common with those teams. They win because the coaches demand this from their athletes and the athletes buy in. Most are year round runners and nearly every day in the year is structured. Coaches oversee each day unlike the self initiated summer running from years ago.
Nothing wrong with hard work but there are also very good hs coaches who tone it down a bit with their athletes. These coaches prefer undertraining their athletes in order to keep them healthy and allow for a patient development of their athletes. They instill a passion in running (not just winning) and encourage kids without too much pressure to win now. It is always great when these athletes overtake their competitors who were pushed hard, overly structured, and losing passion for such a great sport.