Whilst I've got every sympathy for the pressures aircrew are under together with unhelpful ATC, the point already made that the -5/+10 is for our use not yours must be reinforced 'cos I don't think all pilots realise that. I've started aircraft up when they've called at slot time +3 and say they can make it to the hold by +10 - fine but I have to find the gap to get them away - or try to re-negotiate the slot - or worst of all tell the aircraft to return to stand when a two minute wait at the hold busts the slot. All the above create pressure and degrade safety - that's not acceptable.
Can't speak for our European counterparts, but we will be as flexible as we can in an effort to provide the very best service to you (honest!
). However in order to do that, we sometimes need a bit of extra consideration from the flightdeck about what you are asking us to do.