Looking at the 8-hour day from the inside, employee, perspective is one thing. But it's not the only one. There is another reason for the 8 hour workday, main

Looking at the 8-hour day from the inside, employee, perspective is one thing. But it's not the only one. There is another reason for the 8 hour workday, maintaining real-time business-to-business interactions with a single shift workforce. An expectation has been built up that businesses will be open from 9-5. This allows businesses to handle person to person interactions on an expected schedule. As a rule, if you need to contact someone for business you call them during this time. Some companies can do with the delayed response form of email but phone and face-to-face conversations still hold weight in non software centric companies. Some companies might establish their own culture, between a limited number of parties they interact with. However, if businesses at large started shifting their hours all over the place it would make things very confusing for a new player to establish business with them.