High on approach:
A) Reduce Power to increase ROD
Lower Nose to retain airspeed
or
B) Lower nose to maintain flight path
Decrease power to maintain airspeed
either equate to the same thing, however A tends to take a little longer than B, which when combined with increased inertia, leaves B as the better alternative.
PPL teaching generally assumes low inertia aeroplanes where under some circumstances you may not have sufficient power to maintain the desired airspeed. As a result, PPL teaching traditionally involves using attitude to control airspeed on an approach.
In contrast the teaching for turning, involves using attitude or pitch to maintain height/ altitude whilst power controls speed. Possibly, because it is normal to accept a loss of 5 Kts in a medium turn the power/speed relationship is overlooked.
The next time you fly a visual approach, try method B, you'll probably never go back to method A again unles you fly TMGs.