I honestly believe there are no hard and fast rules when it comes to SOP's.A good pilot will use his/her best judgement when it comes to SOP's.Restricting yourself to a rigid and literal guideline when in a constantly changing and dynamic environment is unwise.Kind of like CRM.An authoritarian(undesirable in CRM terms) pilot may well perform brilliantly under pressure and save hundreds of lives.Likewise,a "people person" who scores great on those psych profile tests may kill everyone on board.We just cant know.No hard and fast rules.
Willful disregard of SOP's is incorrect but thinking outside the box and airmanship is certainly not.Airmanship can diverge from SOP's.Nitpickers who trade airspeed for altitude after engine failure when VMC(Chicago-this one changed the rulebook..if you have V2+20 keep it!).A pilot(especially a Captain) who checks only those pre-flight items as laid down in the SOP manual as being his area of responsibility(Helios-Pressurization mode selector).A pilot who shuts down an engine prematurely after entering volcanic ash to prevent damage and facilitate a later relight(BA).A pilot that doesnt descend at Vmo to the nearest airport when a source of smoke is not immediately identified(Swiss-again this changed the rulebook but nothing new to airmanship).A pilot who can brilliantly adapt to a situation for which there is no SOP or even a checklist(Sioux city-Qantas turning off all ADR's ..not in any checklist or SOP!!).A pilot who is wary of any SOP that forbids the non-use of the AFDS or any part thereof.Automation complacency/confusion is a big killer.A pilot when told by ATC to "expedite" leaving the runway doesnt because the taxi speed limit will be infringed.A pilot who doesnt put every single bloody light available to him when taking an active runway because the SOP says only "when cleared for takeoff".
It boils down to common-sense,experience and knowing what you're doing.But they cant write a manual for that so instead they write a manual for the lowest common denominator.Its a guide.An important tool.But by no means a panacea.As an airline Captain,you need more,much more.