My answer to Are Americans workaholics?
Answer by Ken Larson:
We are culturally wired to get things done and get them done now. We spend more hours at work as a result and not always productively.
As I traveled in other countries and negotiated with their cultures, they marveled at how I wished to fly into town, sit down and get it done and leave the same day or the next at the latest.
Most of the countries I visited in Asia, the Middle East and elsewhere wished to socially interact, show me some hospitality for a day or two and then talk business. They were uncomfortable in doing so without getting to know me personally and quite honestly thought I was nuts for not taking more time off and working a 60 hour week.
The answer to your question is simply a very unique American work ethic that I found over 36 years was not a very healthful one.