While I occasionally see people estimate their truly free time, some folks apparently did thoroughly time all activities, and their results are way, way worse t

While I occasionally see people estimate their truly free time, some folks apparently did thoroughly time all activities, and their results are way, way worse than 40 free hours a week. Alas, I've seen only a second-hand mention of that experiment, and don't have a link or names. That's also why I don't want to say the exact hours figure here. I'd like it very much to find a sourced study like this, even if not really scientific.