There was nothing resembling “flight instruments”?
That's the issue I have with mnemonics - most of them aren't specific enough for me.
"Check flight instruments." OK - now what?
I now have to pull from memory what instruments to check (call out) and what the specific response should be. This ain't full proof. I've gotten bitten by this many times because recall isn't consistent. I've noticed I miss item especially when rushed. If I've got specific items in my checklist for each instrument, I have less likelihood of skipping over something.
(BTW I never did gyro checks before because I didn't know I needed to check them. After all, they aren't required for VFR flight. But now that I do know how to do them, I've incorporated them into my checklist.)
The other thing is that, in the case of instrument checks, different checks on the same instrument are done at different times. Take the DG. One check is done right after master is turned on. DG ... "On and running". Next DG check comes during taxi. Taxi DG ... "Turn direction confirmed, Ball opposite turn." Oil pressure - checked on start up and at runup.
Vacuum gauge, engine dummy lights, fuel pressure, fuel flow, egt, & oil temp instrument checks are part of the runup checklist.
So for me "instrument check" just isn't enough.
Not knocking mnemonics, if they work for you, great. Me? I find the simple most useful (GUMPS, IM SAFE, AVE F, MEA) because they are not complex. But MARELOUS VFR C500? Just give me a checklist.