Christoph Roser in "Faster, better, cheaper in the history of manufacturing from the Stone Age to lean manufacturing and beyond", about England switching from the 15h workday to an 8h workday back in the 19th century:<p>> As is to be expected, working fewer hours per day improved productivity per hour. However, what totally surprised employers was that in many cases, the employees were able to produce more in eight hours than before in 14 or 16 hours, not in relative comparison but in absolute numbers! A worker, in eight hours of work with 16 hours of break in between, produced more per day than the same worker did before in 14 to 16 hours with only an eight-hour break in between.