I suspect there's probably a balance - my Russian trained piano teacher was tough, but also threw a lot of music in front of me. We played easy songs in the beginning eventually building in complexity and a lot of variety with theory mixed in. There was never a strong focus on posture or anything like that.

She also didn't believe in using mnemonics to memorize notes - that knowledge would just come from repetition. Though she did hit me pretty hard when I messed up so not sure if that's good or bad.