> jamming people of the same age in a room for 6-7 hours at a time is far less effective...

This may be true, if one is raising a philosopher-king or something. In life I'm thrown into situations where I'm jammed together with people in an "ineffective" manner all the time. If extra-curricular programs are more effective they can deal with both environments. Personally I had some effective, good teachers in school as well as some ineffective team coaches.