When I train pilots in these various types of planes, I will tell them the I will remind them once, but not a second time, to speak the gear position out loud twice.
Quite right too. I totally agree. Most ab initio training takes place in fixed gear aeroplanes and therefore it should not be "undercarriage down and locked" as often taught but to be correct "undercarriage - fixed".
I'm not a lover of mnemonics because they too easily become thoughtless. 'bumffpitchh' and forever onward - this one can get longer - is just silly and can only serve as a distraction. If your going to use a mnemonic keep it short, you should know what to do.