My sensei said that some advice from Japanese Admiral Yamamoto on training went: Show them, explain it to them, make them sweat and then praise them.
My sensei said that he uses: Show them, explain it to them, make them sweat, then criticize them, tell them what’s wrong.
If you praise students they think they understand it and stop improving. Just tell them “dame” (dah may) and make them do it again.
Seito Bugei Juku 