SOPs
SOPs are there to keep all crew members on the same "frequency". However what I found during my career was the "know it all" chief pilots who insisted in changing SOPs from the manufacturer's recommendation to their own. Here are pilots who had nothing to do with the design, building, flight testing and certification of the aircraft but thought they knew more than the manufacturer.
One case in point was the introduction of a procedure that was different to the manufacturer when capturing the GS from above. The "new" procedure caused chaos when approaching the FAF and had the 'plane reaching for the skies at a time when the pilot was attempting to do an approach to LAND. When I e-mailed the manufacturer to clarify the result of this "new SOP" they said " It is why the SOP says to do it that way". They knew what would happen if you changed the published procedure. Quite frankly I am appalled that the governing bodies in each country allow airlines to do this. They should insist on the airlines presenting proof that the new SOP is essential for the safe operation of the aircraft and that it is better that the original manufacturers SOP.