Great reply. I agree that employees often drive themselves this way - but I think it often still comes down to company culture. There is a general industry culture of doing this, and putting incentives in place that counteract this is one of the things I'm trying to argue for.
Erin and I actually have a 10am-6pm rule. We do sometimes break this, as you'd expect, but we find it to be productive. I do think working on something that you have a substantial stake in - generating value for yourself - is very different to working for someone else, where you're ultimately generating value for them. Nonetheless, the productivity findings I linked to still stand, so it's a good idea to institute rest, breaks, etc for yourself, too.