My kids' school goes from 8:30 to 5:00. I agree it is a long day. But....they have an hour of PE every day. They have one hour and fifteen minutes for lunch every day, plus two other breaks throughout the day. They have art, music/music theory and foreign language every day. The long day does allow a lot more time for things other than just the regular core classes. And the working parents like it.
Meanwhile, DS's school runs 7 hours and all grades except K get a whopping 20 minute recess + 20 minute lunch, unless those are both 15 minutes now. Extras (PE, art, music) on a weekly basis only. I hear it's even worse in some city schools, with recess eliminated entirely. I do think more running around time is needed, and less sitting indoors. I don't think one should have to go to a private school for the exercise!