jack11111 Perhaps it’s better to ask you to point out how high you should be at the far end instead? Reading through the regs EASA i don't see any such limit but perhaps you are right if airlines add additional constraints in the takeoff data calculations but knowing the industry for some time now i have serious reasons to doubt that.
If you want to maximize the payload for a given day and runway there is no need for more runway ahead since you are already committed at an earlier point to go. Clearly there are issues with margin and assuming a proper technique and as always other assumptions in play, it’s at least from a performance standpoint i don't see an issue not using the whole runway for the run if needed.
But that assumes you lose an engine at V1!
It means at V1 you need to take the first action to stop or if deciding to go you still have the performance to go. And if deciding to go it means you still should be able to be airborne at the far end taking into account the lower acceleration due to one engine.
Flap config, derate, assumed temp, bleeds, etc are just the variables at hand to get to the point where things work out for a given payload and data to minimize costs wear and maximize payload which i don't see any reason for them not trying to go for at every takeoff.