I take the bus to work at 1:30pm, and to my surprise I constantly find students on the bus. Not hordes, but there's always a few. Isn't it just a bit early for these kids to be out of school? Perhaps they are delinquents.
The earliest school dismissal I ever experienced was back in middle school: 2pm, and even then I thought it was nuts to be let out that early, because it meant school started at an ungodly hour of 7am (I was never a morning person). As I reflect about it now, my teachers had to arrive earlier than that. Sleep is overrated, I guess.
My first two years of primary school was in China, and school in Asia is an all-day affair: the day begins promptly at 8 o'clock, and we didn't start walking home until after 5. It was de-facto, full-time daycare service for the parents because school hours complemented normal adult work schedules perfectly; no one needed to take off work early to pick up their kids. In that regards I think the system in Asia is more conducive to workforce productivity.
There was a two-hour break for lunch and nap time, so cumulatively classroom learning hours was the same. There weren't beds or anything for naps, we were tiny enough to lie down on paired desks or chairs. I didn't appreciate it back then (I've hated naps since I can remember) but looking back now I think structured naps are an excellent idea, especially for little children. Not only is more sleep always beneficial, kid's attention spans being short as they are, having a sleep break in between morning and afternoon ought to help learning retention tremendously.
Obviously, such a system would never get implemented in America (because "freedom"), though I bet a sizable amount of parents wouldn't mind sticking their kids in school for longer hours. Children sleeping on desks and chairs (or floor even) would be considered torture here in the States so schools would need dedicated dorms, and who has the money for that?
So instead we've got kids let out of school early in the afternoon and making a ruckus on the bus, as they are wont to do. Perhaps I'm just an misanthropic curmudgeon who's getting old.