I once worked for an operator who wouldn't let you crossfeed fuel without consulting the checklist, because crossfeeding was in the aircraft type's non-normal QRH. Sim checks were an exercise in 'fly-by-mouth'.
Traffic has it right - all checklists should be used as 'aide memoire' and sure, if it is something complex that you don't understand, you really need to look it up and proceed on a 'read and do' basis.
But, surely, only the most totally mechanically-inept would watch a system overtemp or run away or run out of oil while riffling through pages of a QRH to find the most likely checklist instead of at least throttling back or switching off the gadget causing all the warnings, then getting in to all the detail offered by the QRH?