Dd1's school teaches 17 subjects in Y7 but is slightly different - ordinary state school but they sort of rotate subjects.
Rotate these every 7/8 weeks: sewing/ wood work/ drama & dance/ cooking (2 hours a week)
Rotate each term: Religious Studies/ History/ Geography - 6 hours a week. Lots of group work, excursions & projects. This school is big on using this 3 hour block 2x a week to also instill study skills and lots of reflection about how to do it better next time.
PSHE - taught in assemblies & as part of form
PE - 1 hour a week
Art - 1 hour a week
Music - 1 hour a week
Science (combined physics/ chemistry/ biology) taught as 2 simultaneous units running 2 days a week with one teacher and 1 day a week with the other.
Maths (3 hours a week)
English (3 hours a week)
MFL 3 hours a week
ICT (Computing) 1 hour a week
The school has academic departments/ groups - and I get the impression the teachers are specialised & usually pretty experienced in these subject areas.
I don't know but suspect the rotation thing is about using limited staff in some subject areas more effectively.