When the 777, back in 2007, began to push the envelop of the ETOPS, I read somewhere (I don't want to to misquote) that executives of compagnies and regulating authorities need to consider how would they feel if in a flight, going single engine beyond 180 minutes, are members of their families flown by an average agency pilot in night and bad weather. I tried to quote as close as I remember it.
One can argue that such a personalization is not a good decision making tool but I think it has some merit.