At my office they seem to be biased against this -- whatever time you get in, if you disappear before 5 there's a sense that you're shirking. And this despite what is, overall, a super healthy culture. There's no stigma at all about showing up at 830 and leaving at 1700, but showing up at 700 doesn't seem to allow you to leave earlier without incurring raised eyebrows. I wonder if this is unusual, since I've not experienced it before.