My kids are 7 and 9 and I like to follow the every-other-day philosophy. When they do camps or team tennis in the summer, I do as much as possible on clay (Har-Tru) and rest on the weekends. They also play other sports during certain seasons and less tennis. They are not pro track, but tennis is their main sport.
"More Sureshs, less Maxima for a better TT." - Power Player