Just keep in mind that we all gained our experience in different environments...
I am sure (although I don't know) that Offshore in the North Sea is over regulated, whereas flying offshore out of places like Sudan are still pretty much Bush operations....
It is difficult to understand someone's requirement to use a "rule of thumb" (because that is all he has got on hand where he is) if you are flying in the North Sea with all Bells and whistles, even with ground crew preparing your load manifest for you and delivering it to your cockpit with a steaming mug of Joe's!
(exaggerating for dramatic effect).