That would kinda assume POHs are infallible.
They are not...technology changes for starters. My Bonanza POH specifically says don't operate lean of Peak EGT when that is clearly not a problem if you have the technology fitted...which wasn't yet invented when my POH was written in 1970...and the 'current' A36 POH is exactly the same part number and word for word identical...37 years later!!!
Certainly in an airline setting you absolutely must follow SOPs...99% of the time...but there are times when they are not sufficient...even the Boeing QRH preamble suggests the contents are only a guide. Too, airline SOPs are merely what the current management desire and they change constantly. New Fleet Check and Training Manager into the office and within weeks he is putting his stamp on things...how HE wants things done.
Literally one week X is an absolute requirement that if you ignore will get you criticised and the next week X is out (and if you keep dong it you'll be criticised) and Y is the current thinking...and will get you in just as much trouble if ignored.
Common sense is important too...just a shame it is so uncommon.
