You appear to have stumbled upon what's referred to as the "point and power" technique - much loved by instrument instructors and very relevant to a big jet like a 737.
But in VFR in a single engined light aeroplane, really I'd stick with the classic pitch for speed and power for rate of descent. If this takes a little getting used to after developing an initial bad habit - live with it!
And as I said, I would stick with one instructor and their way of doing things as far as you can. Neither will be wrong, but you don't need the chopping and changing.
G