I got the feeling that it depended on your social status within the team. If you were seen to be a producer and got shit done, then sure whatever, take a nap -- just keep it up. And pretty much everyone I met was someone who got shit done, but a lot of people who get shit done won't let themselves take a nap at work. Even if it's good for them.

Some people still took naps, and I get the sense that the others felt napping would be a violation of a personal code, rather than something consciously felt as a cultural pressure.