Ahh, spilled my baggage there. Thought we were talking uni.
I went to a pretty good HS. Good because it was in a well-to-do area, while down the road in Trenton they had metal detectors at the door. Kinda inequitable but not simply the result of gerrymandered municipal boundaries. More like one of those 'society at large' things that heavier funding alone wouldn't automatically solve. Couldn't hurt either tho since I imagine the teachers down there were asking themselves your kind of questions.
Yeah, a long summer is nice for letting kids be kids but up around HS age it's getting silly. It's not like you're out making mud pies at 16. If it was a 'recommended option,' looked at favorably by unis, and (no harp) free then maybe summer school would become more the norm.
And I hate to say it, being all libtardy and egalitarian, but if I had a kid in a US school, I'd want problem students removed from the general population and put in a tier 2 place. Not a less funded place with cobwebs on the ceiling or something, but just elsewhere. Possibility of coming back etc, but the threat of expulsion/reassignment would do wonders for discipline with most kids, and the ones who are never going to give a shit get disappeared.