We are 'encouraged' to work late on Tuesday and Thursday, and anyone with a priority 1 bug has to resolve that issue that day (if possible).
A few people work late every night, and a handful at the weekend. We are really left to govern our own time. If you have bugs, try clear some. If not, help someone (although I am unsure if that goes on).
My own day usually starts between 7 and 8am, and often finishes between 10 and 11pm. I am only telling you that because the big bosses might read it and I will get some sweeties.