From now on, if you can finish your work week in four days, you will be allowed to start your vacation on Friday. Are you happy? Amazon implemented this type of time management last month. Employees in KPMG's U.S. offices and Uniqlo Japan can choose a four-day work week, and small technology startups such as Basecamp and Reusser Desig also advocate this kind of management.

Working four days a week, we can give examples of its benefits from various angles: the longer the rest time, the better it can help people recover; they have more time to gather with family or relax by themselves; even commuting expenses and office lights are saved on the subtracted working day.

Amazon’s four-day work week pilot project has brought this system back to discussion, but in fact this is not a management innovation. It appeared much earlier than we imagined. In the 1970s, labor experts discussed the feasibility of doing a five-day job in four days with three days off a week. In 2008, researchers at Brigham Young University conducted a survey on employee attitudes, and 4/5 expressed support for the four-day work week. The governor of Utah in the United States therefore issued a decree mandating that 17,000 state government employees comply with the four-day work system. His original intention is to save energy, improve air, etc. By 2011, it was discovered that the expected results had not been achieved. Just in April this year, South Korea became the second overtime country in the world with an average of 2,357 hours of work per year, so it began to implement a four-day work week and seven hours of work per day. The first reaction of netizens was: Will wages be reduced?

This is a matter of balancing working hours, work, and wages. The employer pays wages to purchase labor force to complete the work, and the boss is willing to let the employees go as long as the work can be completed. Has anyone ever thought about what those four days would look like if wages were not reduced and Fridays were taken off? 8 hours × 5 days = 10 hours × 4 days. Daily working hours will be longer if overtime is encountered. Of course, if someone feels that there is room for improvement in daily work efficiency, there is no need to face the embarrassment of working overtime for 10 hours a day.

However, it has been experimentally proven that if the continuous working time exceeds 10 hours/day, the efficiency will decrease. John Pencavel, director of research at Stanford, said that during World War I, because weapons and ammunition could not meet demand, British factories desperately extended working hours in the hope of increasing production. But when the working time is increased to 14 hours, the output is the same as working 11.2 hours.

Allard E. Dembe, professor of public health at Ohio State University, has been studying the impact of long-term overload work on human health. He published an article on the international financial website Quartz and stated that the four-day work system will create additional potential risks for the human body. “Most of the research I've done shows that people are at greater risk to their health when they work more than 12 hours a day. ” Dembe said that when the normal tolerance range is exceeded, stress and fatigue will continue to accumulate, making it difficult to relax.

Another study by Dembe compared the working hours and health status of American citizens in the past 32 years and found that women who work more than 12 hours a day are three times more likely to suffer from heart disease, cancer, arthritis, and diabetes than ordinary people; they are also twice as likely to suffer from chronic lung disease or asthma.

Nowadays, people are tired from working five days a week. If they work all four days in order to squeeze in a day off, it may be the straw that breaks the camel's back. Is it worth it? Daniel S. Hamermesh, emeritus professor of economics at the University of Texas at Austin, said that 10 hours of work can easily make people bored. Everyone has different needs, and flexible working may be a better solution.