My school has only a few dozen students — is Klasku overkill?

There is no minimum student count. The smallest plan is built for a single-branch school, and the fewer students you have the faster you are running: branches, classes, schedules, and students can be entered by hand in one afternoon, with no import at all.

What decides whether it fits is not the size of the school but whether you are still counting remaining sessions, chasing payments, and messaging parents one by one. That work does not shrink in proportion to student count — in a small school it is precisely what eats the owner's own time.