That wasn't my experience. Like I said 10-20% of people could genuinely get more done in their 12th hour and such. It doesn't mean that they never got up from their desks, but it was true that they couldn't get that amount of work done in 8 hours. And it went on for months.
That said, there was lots of downtime, mainly for people whose brains were burnt like mine. Never multi hour lunches though.
It would be surprising if on a talented team there simply weren't people who had much more stamina than others, or just enjoyed their work much more. I'm not saying there's something to be glorified or emulated there.