Crews are encouraged to follow their flight plans which assume an ideal world with no competition for flight levels. In practice, crews learn when it is better to climb higher than desired earlier in order to have an optimum level later in the cruise.
It happens in Big Airways out of HKG homebound at night, SE Asia homebound (especially), India homebound, Africa homebound, and southbound approaching the N African coast. Very often we are just too heavy to manage it.
The 747-436 default uses reduced thrust up to about 25,000' when full thrust cuts in, so reduced climb power has evaporated at that stage. There is a further reduced power setting that must be manually selected and significantly reduces power, but if you are scratching for maximum climb, it is of no use.
We are at all times conserving our engines, and not keen to whack full power out of them.