I'm currently working on my PhD. I had a 4.0 in undergrad and I always came first in my class from high school through to university.
I am your token nerd when it comes to school.
And I can tell you right now...Taking rest, seeing friends and enjoying life make me more refreshed and energized to work harder when I get back to work. Even when I am taking rest and doing nothing, I get bored and want to get back to work. It's all about balance. Kids need their summers off to explore, enjoy and experience aspects of life you can never get in school.
If that's how you feel, then we should eliminate holidays, weekends, etc and just always work.