How much is too much?

The American Academy of Pediatrics' Council on Sports Medicine and Fitness recommends that children devote no more than a maximum of five days per week to any sport with at least one day off. In addition, athletes should have at least two to three months off per year from a particular sport during which they can play another sport, utilize different muscle groups, let injuries heal, refresh the mind and work on strength, conditioning and proprioception (balancing exercises) to reduce the risk of overuse injuries.

Do you think these are good guidelines?