Everyone from Richard Branson to Bill Gates has talked about tech advances disrupting the regular work schedule, those five-day work weeks with just a couple of vacations a year.

Now Adam Grant, The Wharton School's top professor, says instead of the typical 9-to-5, our work days should end two hours earlier too.

"[L]et's make work days shorter: they should finish at 3pm," says Grant, an organizational psychologist and New York Times best-selling author, in a recent LinkedIn post.

"We can be as productive and creative in 6 focused hours as in 8 unfocused hours," writes Grant.

The post has since garnered thousands of likes and hundreds of comments.

Research suggests Grant is on to something: In one experiment in Sweden, employees at a nursing home adopted a six-hour work day (with no change in pay), which resulted in improved productivity and worker health. Other research has also linked decreased productivity to an increase in the number of hours worked.

In the LinkedIn post, Grant was weighing in on an Atlantic article about the time gap between when school and work days end, a bane for many parents. But it's not the first time Grant has given his stamp of approval to less work with more productivity.

"Productivity is less about time management and more about attention management," Grant tweeted in July, highlighting an article about a successful four-day work week study.

For the study, a New Zealand company adopted a four-day work week (at five-day pay) with positive results; the company saw benefits ranging from lower stress levels in employees to increased performance.

Billionaire entrepreneur Richard Brason also acknowledged the future of work could include "three or four day weekends" on his blog, saying: "By working more efficiently, there is no reason why people can't work less hours and be equally – if not more – effective. People will need to be paid more for working less time, so they can afford more leisure time. That's going to be a difficult balancing act to get right, but it can be done."

Even Frances O'Grady, the general secretary of the Trades Union Congress (an organization in the U.K. representing trade labor unions), voiced her belief in a shorter work week in September, saying in a speech in England, "I believe that in this century, we can win a four-day working week, with decent pay for everyone."

For his part, Grant is lauded as somewhat of a master in productivity. Aside from his role at the University of Pennsylvania's Wharton business school, he has written "Give and Take," "Originals" and co-authored "Option B" with Facebook's Sheryl Sandberg.

Don't miss: 4-day work week is a success, New Zealand experiment finds

Like this story? Subscribe to CNBC Make It on YouTube!