From what I've seen, its more of a culture thing than anything. I've never been explicitly told I'm not working enough, or that I need to work late, or anything like that. You just see your coworkers answering emails at all hours of the night, and working late, and in a constant state of crunch mode. A lot of this even seems self imposed, some people seem to get a thrill out of it, and seemingly brag about how much work their doing, or how late they work. Then they get additional praise for putting in the work. It's easy to get dragged in to this too. There's a sense of guilt that comes when you're only working your 40 hour week and everyone else around you is putting in 60 hour weeks constantly. You start to feel as if you can alleviate their suffering if you only put in an extra five or ten hours.