Is the eight hour workday outdated and irrelevant today?

Is the eight hour workday outdated and irrelevant today? Stephan Aarstol is CEO of Tower Paddle Boards, named the fastest growing company in San Diego and author of a book called The Five-Hour Workday. Not only has he written the book on five hour workdays- but in 2015 he put his employees on a 8am to 1pm workday for three months and says that the switch had an enormous, positive, and lasting impact on all of them.