“Adding more hours to the workday does not correlate one-to-one with higher productivity. Working overtime is unsustainable in anything but the very short term. And working a lot of overtime creates a level of burnout that sets in far sooner, is far more acute, and requires much more to fix than most bosses or workers think it does. (..) Research shows that knowledge workers actually have fewer good hours in a day than manual laborers do — on average, about six hours, as opposed to eight.”
Why We Have to Go Back to a 40-Hour Work Week to Keep Our Sanity