“The eight-hour working day is a relatively new concept, widely accepted to have been cemented by Ford Motor Company a century ago as a means of keeping production going 24 hours a day without putting undue demands on individual members of staff.” But it turns out that’s too many hours to expect people to be productive. WiredUK: The perfect number of hours to work every day? Five. (In my case, they got the number right, but they spelled minutes wrong.)