When asked why this was done instead of following the POH the response 99% of the time was simply "My last instructor told me to"
Happens with other items such as Cessna 152/172 before landing items eg Brakes, Undercarriage down, Mixture Rich, Master Switch on, Magnetos both, Fuel, Harness and Hatches etc
Yet the only before landing checks in the manufacturer's POH (Cessna 172 for example)
are: Seats, belts, Harnesses secure, Mixture Rich, Carb heat on.
Comment: Note seats secure in the POH but not mentioned in "what my last instructor told me to". Note nothing either in the POH about brakes, undercarriage or master switch or mags on. I recall asking one instructor why he taught Masters and Mags as part of the before landing items. Because they start with "M" he said.
PUFF checks on final. Whatever mnemonic takes your fancy. All inventions of some instructors who blindly adhere to 'My last instructor told me to"