Not only is the speed of the RTO significant, but also the take off weight and thrust used affecting momentum.
Even fully loaded with pax, a 747 flying from Bangkok to Tokyo would probably have only around 60,000kg of fuel on board, making it still a relatively "light" takeoff weight by 747 standards, hence the need for "full whack" (non derated power) would seem unlikely. In fact, a max derate would probably be possible.
No judgement, purely info.