I think academic lessons should finish before lunch. Afternoons should be reserved for (elective) music, drama, DT and / or sport. IMO those subjects should not be "academised". They should be coached at a high standard, for an adequate amount of time (pupils should be able to do at least 5 hours per chosen elective per week), and they should not be taught to an exam except for the occasional practical exam offered by professional bodies (ABRSM, LAMDA, SMSCP + productions, competitions etc).
I also think there should be no homework (unless a pupil wants to do extra study...). There should be work in lessons and frequent feedback on that work. If a pupil does not work in lessons then that pupil should get immediate detention lasting until he has completed all the academic work he has missed.