Theres a percieved and sometimes real pressure on many engineers to push themselves past their bodily limits to 'go the extra mile' in an AOG situation rather than be seen to be a rebel or troublemaker by resting when they ought to.
Therein lies the problem - most of us engineers will invariably "do the right thing" when confronted with an AOG situation - but the cost on our bodies can be expensive.
Another danger is the trip home after these sort of shifts - usually the adrenaline keeps me going until the job is done but then find myself nodding off on the shuttle bus to the carpark.
My company is pretty good with trying to get relief staff on site or standing down people after long shifts but still when they ask if you can stay it's hard to say no - just because it's what we do.