A and C, how willing do you think an insurance company will be if a pilot runs out of fuel because he failed to operate to published SOP's? How about if he pranged on landing because he failed to use a profile for landing as detailed in the Ops Manual? The list goes on...
However SPO,s on a multi crew aircraft are the base of good CRM and must be used.
If two private pilots go flying together in a Cherokee then I consider this multi crew. You have the same synergy and dynamic kind of environment. Wouldn't you want both pilots operating to common procedure? Surely so! It really doesn't matter if you have two 15000 hour pilots in a 747 or two 150 hour pilots in a 172, if they do things differently and operate to their own schedule then they compromise safety.
[This message has been edited by Turbine (edited 04 October 2000).]