Early on in my career, I realised that working late is an accepted norm. It took a small stint at a games company to see the flaw in it though. There, I saw a workplace where it was normal to stay until about 10pm just about every night. Anyone who left on time was seen as not really putting in the effort.
And yet, for a large part of the day, I saw people sitting around doing very little. Chatting about that club (Ministy of Sound I think it was - that may tell you the location of the company), about other games, about DJing and (yes, it's those lazy 3D animators again) waiting for their previews to 'render'.
But everyone considered themselves to be working hard because they were going to be there until 10. It was completely flawed. If they had accepted that they were to go home at 5pm, they would probably have got more actual work done and had the evening all to themselves.
Long after that, in television productions, I saw people working late mostly due to poor planning by producers. If your animators need to stay late on a regular basis, you need to hire more animators. Simple as that.
But don't judge me because I have Saw IV on dvd and I plan on actually going home at some point to watch it.