For what it's worth, I thought our senior retreat was a big waste of time, which is a shame because they ran a new program on our cohort and lots of teachers put in a lot of effort and all of that, but to me it was real tedious and our half yearly exams were 10 days after retreat finished. I know I'm the kind of person who needs to keep momentum going with study or else I find it way too hard to fall back into. I really felt like I knew best by wanting to study on retreat (not going wasn't an option, I was excited to go until I was there and thought it was severely ehhhh), but by the time the half yearlies came I wasn't regretting not studying on retreat. I didn't think, "damn if I studied for those three days, ten days ago, I would feel more confident now." So even though I thought retreat wasn't really worth the disruption to school and study for, in the time before my exams I wasn't wishing that I could go back and rewrite those days so I can fill them with study.
I know it's tempting to feel like you're twisting the system to get yourself ahead, but as everyone's said, just roll with it and try enjoy the events of your last year at school (even if it is a 3 day slow retreat). There will be other things you can sacrifice to gain study time (video games, facebook time, etc..) (although I know you're not the procrastinating type, bananna), that won't be days at school that have the potential to give you great memories
