That's interesting that the 40 hour thing came from OR. Will have to look into that. I'm working on my MS in OR right now. I had always just thought that it was based on the undeniable fact that work just kind of sucks after 40 hours in a week.
I still recommend reading Calder, but I would take what I said with a pinch of salt.
https://books.google.com.au/books?id=aCRuuAXx-WkC&pg=PA397&l...