The system should treat all users the same, the problem is more that they allow inbounds to continue and then slap them with a last minute 15 minutes, when it could have been done a long time before. Give aircraft proper slots, be at feeder fix x at x time, not 'about this time' gdp rubbish so that everything departs +-15 minutes or some nowhere near that and then deal with 15 aircraft that should have been well spaced. I can depart right on GDP time, get airborne and get min speed and15 mins holding, then another aircraft gets max speed to fit in front of me, that's where the system makes no sense at all. And that scenario happens regularly, not based on emergencies or medicals, just weird TAC decisions. Then inevitably the max speed aircraft doesn't meet its time and everything gets a further slow down, when we could have been 5 minutes ahead of it even with slow down of 5 minutes.
I always aim to land with an hour+ in the tanks, no point being on fumes when you don't have to, my aircraft starts yelling expletives at me before it gets to FR fuel level anyway, so I'd be dealing with abnormal checklists and reports if I got anywhere near 30 minutes remaining.