Having to only serve one more year in the NYC Public School System, I can safely say that making the day longer and shortening the holidays is pointless.
The fact is, you're not learning anything essential to use in the outside world. You're only learning how to take standardized test. That's all you'll really spend your time doing: preparing for and taking the god damn standardized tests. At my school, they cut the forensics class to make room for another science class that focuses on topics that will appear in the S.T.s. Everyone has to take two or three science classes, and all of the teachers are pissed because the state requirements prohibit them from teaching anything but what will appear on the tests.
Take my 11th grade history teacher. He wanted to really get into the Vietnam war, but because of the state requirements, we could only spend a week on some of the politics that happened in the vietnam era. (and the only politics we could cover were mainly the presidential debates.) He also wanted to teach us about the Clinton administration and what happened (like the First Battle of Mogadishu), but again, state requirements wouldn't allow him to do so.
But what I have and had to deal with for high school was no where nearly as ridiculous as what happened at I.S. 10. Two periods of math, two periods of english, and a science class or two. That's it, that's all you were allowed to do, day in, day out. The whole day was spent preparing for the S.T.s. The school even made it so that we only had a minuet to get to each class, lunch was 30 min. long (if you were lucky) and the school day went from 8-3:30 pm.
The last summer vacation didn't start until the very end of June and school started back up the first few days of September. Everyone joked that we were going to Hogwarts. (the Hogwarts semester starts Sept. 1.)