In 1900, the Ford Motor Company commissioned a series of tests to determine how long a workweek should be to optimize productivity. Ford discovered the “sweet spot” was 40 hours per week. Sara Robinson, in her article Bring Back the 40 hour work week, relays the following story:

“In 1914, after 12 years of internal study, Henry Ford took the radical step of doubling his workers’ pay, and cutting shifts in Ford plants from nine hours to eight. The National Association of Manufacturers criticized him bitterly for this — though many of his competitors climbed on board in the next few years when they saw how Ford’s business boomed as a result. In 1937, the 40-hour week was enshrined nationwide as part of the New Deal. By that point, there were a solid five decades of industrial research that proved, beyond a doubt, that if you wanted to keep your workers bright, healthy, productive, safe, and efficient over a sustained stretch of time, you kept them to no more than 40 hours a week and eight hours a day.”

There was one exception to this rule. Research by the Business Roundtable in the 1980s discovered that a company could get short-term gains by going to 60- or 70-hour weeks very briefly — for example, pushing extra hard for a few weeks to meet a critical production deadline. However, there were 3 key warnings attached to this exception:

Increased hours yield diminishing returns

Increasing a team’s hours by 50 percent (from 40 to 60 hours) does not result in 50 percent more productivity. Most leaders today assume the extra hours will produce an equally matched extra output… but usually this formula fails.

Working an extra 20 hours is effective only in short bursts

If you put in 50-60 hours every week, your production declines every successive week because of exhaustion. When people get tired, they make stupid mistakes that take longer to fix. Focus becomes elusive… and consequently production slows to crawl.  The Business Roundtable study revealed that after just eight 60-hour weeks, the fall-off in productivity is so dramatic that the average team would have been equally productive if they’d just stuck to a 40-hour week all along.

Long-term productivity suffers

Once the short burst of an extra-hours week is over… and your workers go back to 40… it can take several weeks for them to return to their normal output. So, for a while, you’ll get significantly less than a full 40 out of them in terms of production.

Now I’m a realist. I understand your work week likely doesn’t fit neatly into 40 hours. And I’m not suggesting that any work done after 40 hours in a week is worthless… or that you are doing something inherently evil when you do. But be aware of the inevitable productivity decline after you reach the Big Four Zero. You’re not getting the same bang for your buck.

I’d love to dialogue with you on this subject… so leave me a comment to get the conversation started.