Most people are lucky to squeeze 3 hours of actually-useful work into a single work day. In your average office, the rest of the 8-or-10-hour work day is burned

Most people are lucky to squeeze 3 hours of actually-useful work into a single work day. In your average office, the rest of the 8-or-10-hour work day is burned on socializing with colleagues, responding to and reading emails, attending interviews, trainings, or other rote meetings not specifically related to one's job, traveling around the building, eating, taking restroom and Facebook/reddit breaks, and so on. I don't think this number goes up as you expand the requisite work hours or push people against their will. I think people just find increasingly creative ways to avoid real work while still filling the butt-in-chair requirements.