Does "Treat him mean, keep him keen" really work? What is your opinion on it?

Title is pretty self explanatory. But do you think it's a good or bad thing to do because I hear that "technique" I guess you could say is apparently helpful. I want opinions on this because I'm not sure whether it is a good thing to do or not.

Sorry if I put this in the wrong category I wasn't really sure.
Does "Treat him mean, keep him keen" really work? What is your opinion on it?
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