Too glib; they've been holding pretty steady at 8 hours, mainly due to regulation. Other work has increased hours, such as in many areas of health care, for example. Many folks also patch together multiple jobs in order to achieve a livable income and can work upwards of 12-16 hour days. I know several, personally.

Keynes predicted we'd be down to 3 or 4 hours a day by now, but that never happened due (partly) to the ever-increasing competitive ability/imposition that technology allows managers and shareholders to impose on labor in an effort to maximize economic potential and productivity.