I've never kept office hours as long as 9am to 7.30pm. Too long in one location turns you into a monkey banging away random crap on a keyboard.
I don't know of anyone working until 7pm.
Almost everytime I read an article on rudebaguette.com, I feel like either I live in a foreign country, or they do.
At least this is how most of the companies I've worked for and most people I know. But some do choose to eat at their desk, but why? I sit there all day.
I find doing this sort of thing over a few weeks really starts to grind the psyche down. Not enough time spent on a mix of things is problem, I think. How people could do it as the norm is beyond me.
While I'm here, I'll just leave this: http://www.bls.gov/tus/charts/chart17.txt and this: http://www.bls.gov/tus/charts/chart11.txt.