Great insight! I wouldn't have thought about it this way, although I can think of quite a few instances where this approach would have been more than helpful!
Great observation! It's not about the duration of the 8-hour work day though, but the concept of it. It's about doing something for a specific amount of time and then receiving a pre-established monetary reward. You're right, it could be a one-hour or five-hour workday. It just happens that in our days it's an 8-hour workday/40-hr. work-week.