1. No one stops you from keeping "zone" feeling during lockout, you can just drink something (what actually helps to think a lot is to drink regularly) or sit for a while with closed eyes thinking about problem, etc.
1a. I sincerely think that regular breaks actually help solving problems (at least in some cases).
2. Schools use timed breaks and in rare cases of interesting classes they do not discourage students to learn. Of course schools should be optimized more, I'm not arguing that.
3. Timed lockout is not target, invented just to prevent illness, it is also a method. Method to teach self discipline, even to begin teaching self discipline in some cases. No one will tell you how to optimize living when you'll grow up, that is why we read a lot of articles about people who burn out on a job.
Later it is insanely hard to go from super lazy, undisciplined student to focused worker.