So that's how your systems works. It sounds really interesting.
I like the focus. Makes you choose something and stick with that.
Our system is a bit dull. You more or less do all the subject, all the time. That's about 14 of them. Some of them (like psychology, logic, Latin, sociology, philosophy, Greek in classical schools) last only 1-2 years, and then get replaced by another subject.
In most schools you also have a choice to lose some subjects (but this mostly means having less classes in a week) in favor of maths and physics or languages.