There is no right answer !!
Pitch for aimpoint and power for speed seems to be the most immediate way to correct mistakes on a flight path and so for this reason can be used on the final app. Power for ROD and pitch for airspeed works well but there seems to be an inherent lag as one trades against the other. Hence it works well for the part of the app that has no aim point, in my case the finals turn or base turn of an oval cct. Also as stated high perf a/c respond better to using power for speed and "pointing" at the threshold (Velocity vectors in the hud are wonderful things!!).
Doesn't answer your quandary but the great thing about avaition is that your instructor isn't always right.......just takes a long time to work it out.