My 2 cents from a retired guy. If you feel you need the fuel, add it. If you signed for the jet, do what you need to do get where you're supposed to go using YOUR best judgement. Why have a puckered AH for hours on end wondering if you'll have to divert or land on fumes. It's just not worth it. Do you really want to deal with a divert after a mega-hour day?
MG2