I think it sometimes comes down to a matter of choice in working styles. Some people thrive on killing themselves at times. I've been there. I will still occasionally pull a late-nighter because I get in "the zone" and am actually enjoying the productivity and I still get the condescending comments about how if you planned properly, that wouldn't be necessary, but I think that some people just don't get that working like that can actually be very gratifying. I'm getting a bit old for doing it more than about once a quarter, though, whereas I used to do it a couple times a week.