This seems relevant:

"How Not to Ruin a Swimming Prodigy"

http://www.wsj.com/articles/SB10001424052702303674004577434550791785644

"As a coach, however, Schmitz stands out for a devotion to rest and play. No less important than his swimmers' splits is whether they are having fun inside and outside the natatorium. At practice, if the kids seem spent, he'll end the workout midway through and start a game of water polo. "He's a fun loving kid, he laughs with them, he plays loud music," said D.A. Franklin, Missy's mother."

The old adage in advertising was that 50% of the money spent is wasted. In these toxic high pressure school districts how much of that studying time actually is helping the kids improve? Lots of kids are probably way past diminishing returns and deep into negative returns.