Almost thirty years ago, my primary CFI gave me my first checkout in an airplane with a constant-speed propeller...a Cessna 182. He repeatedly drilled me on the routine: always retard the throttle before you pull back the prop control; always push in the prop before you advance the throttle; and never NEVER allow the manifold pressure exceed the RPM/100. Operating "over square" will damage the engine, possibly severely.
This is a companion discussion topic for the original entry at https://www.avweb.com/features_old/why-over-square-is-good