I appreciate that is a good rule of thumb to remember but keep in mind that when trying to fly an instrument approach and you need to slow down, pitching up isn’t gonna do you much good. You need to reduce power and adjust pitch up slightly to stay on glideslope while re-trimming to reduce the control pressure. In other words, you need to adjust pitch AND power at the same time.
You certainly know this if you are currently in instrument training, so I don’t mean to be condescending. But it can confuse new pilots to say “pitch for airspeed, power for altitude” when in reality you’re always doing both, for both.