Where I work, which may or may not be under the jurisdiction of the largest (which may or may not necessarily be the best) ATC provider in the UK, I feel that my colleagues need to realise a few things about these 'early goes', which contribute more to the bad feeling in the workplace than any other issue.
1. They are perks, not a right
2. They are based entirely on the goodwill of your colleagues, on a 'you scratch my back, I'll scratch yours' basis
3. Supervisors / managers etc. are doing you a favour if they decide to take advantage of your colleagues goodwill and let you go home before the end of your shift.
4. I've run out of goodwill. I'm paid to be there, so I'll be there.
5. If I'm there, no it doesn't mean you can go home.
6. If you don't like it, you can go and get a job in the real world.
Rant over.
Can we all be, if not nice, then at least professional to one another.
Rant properly over