That was what I observed when working at EA (I was actually part of the EA Spouse settlement so this kind of comes home).
Probably 10-20% of the people on the dev team just loved it. They couldn't get enough. That includes engineers and artists. They could work from 9am to 11pm for months.
But then management expects 100% of people to be like that. And there's peer pressure not to let down your coworkers. But in reality some people just have more stamina, and can get more done with the incremental hour, while for others it was just clocking time and being a zombie.
I definitely couldn't get much more done in all those late nights, although it in part it has to do with the fact that there was some sort of "schedule". If you know that you can take a day or 2 off whenever you want, you're likely to have more stamina for a 16 hour bender.
Anyway, there is so much human variation in other things; it doesn't surprise me at all that it's true for how many hours you can productively work in a day. I would bet startup founders need that stamina, although I'm sure there are many more components to success.
"That includes engineers and artists. They could work from 9am to 11pm for months."
My experience through various sectors of the software industry (including gaming) is that virtually nobody really works 9 am to 11pm for months. But some people are happy being at the office from 9 am to 11 pm assuming the "work day" includes a multi-hour team lunch break, some random breaks for playing Doom II, Diablo 3 or the newest Battlefield or whatever is hot at the office, lots of slashdotting/redditing/HNing/etc, hours long discussions about what happened on the hot geeky tv show, etc. So what it comes down to isn't even the workaholics vs the non-workaholics, but the totally tech-focused geeks vs the people who have non-tech things going on in their lives.
FWIW, up until my early-mid 30s I was very much the former, so I don't entirely begrudge that lifestyle, but I think it is mostly fantasy that those people are putting in significantly more actual work hours than the other group. Personally, I know I'm vastly more productive putting in 8-ish hours day now than I ever was when I was putting in 16-ish hour "work" days, though everyone's mileage may vary.
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.
I think the main difference is engagement vs grinding. Take gaming for example. How many hours can you sink into that? My personal experience was that I could go pretty hard at it with very little sleep (I know, i know) and still be quite effective. I get the same way when im hacking away at something i love. Right now, im trying to put together a JS debugger for vim. Its 3am here and I can just keep on going.
Now, the same cant be said about writing TPS reports.
Yeah for sure... I just spent about 25 hours in a single weekend coding on my own stuff. And I feel great now. I had that high today, on a Monday! But even though games are somewhat interesting, it wasn't my main passion and I wasn't that good at it, so I got burned out pretty fast.
So bottom line is that it's futile for management to push people that hard. Some people love the problem and they'll put tremendous hours int oit. But you can't force that upon anyone.
On the other hand, perversely, I can see the logic to it. There are 20% of people who are running full stream and being super productive for 14 hours a day. Maybe you just keep everybody in the office so that those people feel like everyone is making a sacrifice too? If you don't care about burning people out, I guess it is rational to keep people in the office if only 20% of people get more work done, if those 20% would leave if everyone wasn't there.
There's a necessary stopping point, even for one's own projects.
A few nights ago,I got jazzed-up on the Vietnamese Iced Coffee I'd had with dinner, and I literally coded all night and into the daylight. I probably started around 8PM and ended around 9AM, working on my hobby project.
And honestly, if I hadn't been jazzed up, I would have stopped somewhere around 1:30AM, to my own great benefit. By the end I was spending half my available effort just staying awake and remembering how my code is broadly structured.
If I'd had to do something other than cycle through compile-run-debug, I would have failed completely. No matter your caffeine or passion levels, at some point you lose sanity points and Cthulhu arises from the depths to eat your code and then your soul.
7-9 months... it's a yearly cycle. So maybe from January or so to August. Maybe only that max intensity for 3 months or so. For a couple months after the game ships there is a lot of goofing off and unwinding.
Lots of people leave the game industry like me, but there were definitely those who did it for 10 years straight.