I've flown for a bunch of airlines. One thing became obvious; SOP's were often at the whim of the C.P. and not always for good rhyme or reason. I was staggered when I first joined the airline business how it was possible to reinvent the wheel, redesign the a/c and how so many airlines chose to re-write the manufacturer's instruction book. I couldn't fathom it; perhaps still can't. I've learnt to live with it, sometime in frustration. I've flown for airlines where they claimed the SOP's to be the approved bible and guarantee of safety. Firstly it was quite obvious that the XAA had not read the whole Ops manual: that was impossible. Secondly the eureka new SOP was changed a couple of weeks later as the line pilot feedback was that it didn't work the way the desk jockeys thought it would. It was often a 'told you so' moment. Thus, I am an SOP sceptic, not in the general sense of SOP's, but in that they are not always the best way to achieve a required task. It is also possible to over SOP a company. I am involved in TQ teaching. The students will join a in-depth SOP airline. They are trained robotic monkeys and guaranteed to survive if they do not deviate. I will debate that. A colleague SFI from another airline is shocked. In his airline , e.g. a G/A ifs flown according to FCTM and the approach chart with good airmanship discretion in coordination with ATC depending on Wx & TFC. In our TQ airline the G/A will be flown to absolute completion, by numbers, with no exemption. This is not the real world. Is it the best SOP? Should it be so? Should discretion be taken away fro the crew? ATC ask if you can abbreviate the procedure and you have to refuse or break SOP's. The same was a classic for years: CAT 2/3 LVO's; maintain 160k to 4nm (ATC) but SOP was F40 at G/S capture. So please, the SOP bible is not always the bible it pretends to be.
What SOP's do is cover your backside in case on an incident. This time "I was only following orders," is a defence. But sometimes it go my goat and irritated the dung out of my airmanship instincts. Times have moved on, peacefully, and the conflicts no longer applies; but sometimes having to teach such stuff just because it's their train set is galling.