Power management basics
Instructors don't usually teach power management as a separate topic, it's the culmination of many small lessons. When we learn to fly, our CFI teaches us to add and remove power smoothly. We learn that rapid power changes can damage the counterweights on the engine's crankshaft and that advancing the throttle rapidly might cause an engine to falter. We learn to set the cruise RPM, then properly adjust the mixture.
Power management in a complex aircraft is more involved. For an aircraft with a constant speed propeller, we control power and RPM separately. The throttle controls power and the propeller control sets the RPM. Instructors teach us to avoid combinations of high MP and low RPM because it can overstress the engine, just as we can overstress our legs by trying to pedal a bike in high gear up a hill. To avoid engine stress, we increase the mixture and RPM before adding power. We reduce power in the reverse order—reduce power, reduce RPM, then set the mixture. But there's more to power management. By learning to manage power properly, we can avoid looking for dirt roads in the dark.