Is the U.S. 40-Hour Work Week "Just Right"?

In a recent article in Time.com, author Geoffrey James noted that the COO of Facebook routinely leaves the office at 5:30 p.m. to be with her children.  However, for years she felt the need to hide this fact before "coming out of the closet."


Almost a century ago Ford Motor Company ran dozens of tests and discovered that the "sweet spot" was 40 hours per week for optimum productivity.  In six of the Top 10 most competitive countries in the world (Sweden, the U.K., Germany, Finland, the Netherlands, and Denmark) it is illegal to demand more than 48 hours of work per week.


So, what do you think?  Is the "standard" 40-hours per week in the U.S. too much, too little, or "just right"?  Would you prefer to work 10 hours per day in a 4-day work week?