@Brandon9000,
As a child and adult, I've always loved the long summer vacation, but I didn't have troubles with learning or retention and neither did either of my children, so as you said, it was simply a time to rest, relax, have fun and look forward to the new school year.
But for students with learning disabilities, the long summer vacation represents a hurdle to learning and retention. For those students, every September and October are spent reteaching and relearning basic concepts - especially in math - which is cumulative so new information can't really be added or absorbed until the old information is mastered.
I do the like the school schedule here in England - six weeks on - 1 week off - six weeks on - two weeks off for Christmas - six weeks on - one week off - six more weeks on - two weeks off for Easter - six weeks on - one week off - six weeks on - six weeks off for summer vacation
*(approximately - sometimes it's ten days instead of one week)
Anyway - I love it as a parent - and I'd love it even more as a teacher. During that LONG uninterrupted span from after Christmas to Easter it's really, really hard to keep the kids motivated and then as I said, a lot of these kids come back after the summer break having forgotten everything and you use about six or eight weeks - or about twenty percent of the school year - reviewing what you did the year before.