In my experience demands for working > 40 hours, nights, weekends, etc. almost always comes from management and planning failures.<p>What makes this scenario occur so often is that the business side wields too much power when it comes to culture, estimates, technical decision making, etc. For them you solve a problem by throwing more time at it and passing responsibility when possible (along with a few extra meetings, for good measure). Not only does this approach work poorly for development, but they are often the "final stop" in the product lifecycle, thus making it impossible to avoid taking responsibility, even for others work (like, say, for incomplete or nonexistent requirements).<p>Perhaps worst of all is that surviving these crunches makes things worse as the wrong lessons are learned and the process continues to repeat itself as those who push for change become disgruntled and leave.<p>Personally I've noticed a correlation between the pushing of "team culture" and toxic environments like this. The most egregious example of this was when it was suggested that I work unpaid on the weekend to "complete the sprint work as a TEAM."