Nobody is stopped from working longer hours, but the expectation culturally is that you should probably be doing something else instead of working on Sunday.
Sunday was just an example. Nobody is stopped from working if they're movitated to do so, but we generally discourage each other from working overtime unnecessarily. I personally work 32-hour weeks regularly and still contribute meaningfully.
And then, I go backpacking or bike-riding or something that tends to be demanding physically and relaxing mentally—I find it helps me keep a healthy balance. I know there are plenty of people that don't crave that reprieve though, and that's totally okay as well.
There's weekends where I'm working on a particularly interesting problem where I'll work through the weekend because I want to. The big difference is the extrinsic pressure is missing. Nobody has to.
