The school my kid attended had both AP and IB classes with a trimester schedule.
Kids did a fair amount of summer work before school started to ensure they’d hit the ground running and be ready by exam time. One good thing was that the second trimester final was good review of material covered to date for the AP ot IB exam.
Yes, the time after the exam was still used for academics. Most kids were actually pretty engaged academically so didn’t stop caring after the exam, but itdid change the energy.
I like your travel idea or a service project or a performance or really anytime that made the subject come to life a bit. That time after the exam lends itself to that.