I have noticed that a lot of people treat work as a social event. They spent a significant amount of their day shooting the shit. As an introvert who can't stand smalltalk, I don't. I think 40 hours or more makes sense for employees who spend half of their day chatting or surfing the internet. When I'm at work, I am working. I still do more than 40 hours, but I'm not sure if it's sustainable. I was recently asked to increase to a minimum 48 hour workweek and turned it down because I know it would upset my work life balance and not increase my output.