I agree with those saying that days off should just be rearranged for a variety of reasons.. one long block is a lot less useful than many shorter blocks of time off.
First, it can get boring, and it certainly gives you quite a bit of time to forget things. Even if it is fun, the thrill dies quickly, and there are rarely many remedies to this.
If anything, in my experience summer was in some ways a chore, as parents didn't have time to watch me all day or thought I should be active, and had me do annoying daytime summer camps that took a lot of the freedom out of summer. And I consider my parents comparatively responsible people.. they just had life to deal with, that wasn't their fault. If breaks were shorter, parents would be a lot more able and likely to take out time for kids and do things with them, instead of seeing finding things for their kids to do as more of a chore. I know on spring break we generally did something, and it's just a week off. Contrast this with summer where maybe we took one week trip (generally not even that vacationy.. just family or something), and the rest of it was pretty uneventful.. certainly the break should be there, but it need not be months long.
I also think I would've welcomed further breaks during the year, particularly as I got older. Stress mounts easily and quickly, and while summer is nice and stree-free, the rest of the year is not. Breaking up the year better would likely help destress students more often, helping them to learn more effectively.