The problem with mnemonic’s, in addition to the points ably made by Pilot DAR, is all the systems are not created equally.
For example take the “F” for fuel. Before take off on some airplanes the selector should be on both, on others the fullest tank and on others, a specific tank (eg main or fuselage). On some airplanes the electric boost pump must be on on others it is imperative it is off.
The only way to know these possibilities and permutations is in the aircraft manual, which is also going to have a checklist, so why on earth would not use that over some mnemonic that somebody made up.
One of the biggest problems in flight training is made up Shyte from the good idea club that mindlessly gets passed down to each new generation of instructors, just like the lunacy that you have to abort a takeoff if the door opens because it could come off and hurt the airplane