Forty-five years ago, the federal government decided that a number of holidays—Washington’s Birthday, Memorial Day, Columbus Day, Veterans Day and eventually Martin Luther King Jr. Day—should fall on a Monday instead of the dates those holidays were traditionally observed.

The first four holidays switched to Monday as a result of the Uniform Monday Holiday Act, passed by Congress in 1968. MLK Day, established 15 years later, followed the same pattern, and is celebrated on the third Monday in January. Perhaps they were just following the lead of Labor Day, which was established by Grover Cleveland in 1884.

What if we were to switch all those holidays from Mondays to Fridays? For busy offices that naturally tend to slow down at the end of the working week, it seems like it would be a natural choice.

According to a time-use survey conducted by the London School of Economics and Political Science, Fridays are the least productive of the weekdays, tapering off to 3...