Four-day workweeks are becoming relatively common in Europe, but they haven't fully caught on in the United States. The fast-casual restaurant chain Shake Shack is looking to start a trend. Faced with a struggle to retain quality managers, the company is decreasing its workweek at its Las Vegas, Nevada, location.

The turnover rate in the hospitality sector was more than 70 percent for the second straight year, according to the U.S. Bureau of Labor Statistics, and three in 10 restaurateurs say staffing is a challenge.

The chain faces an interesting dilemma: It's looking to expand—the goal is to develop 36-40 new sites this year—but doesn't have the managers to make it happen. Rather than slowing down its growth plan, Shake Shack is experimenting by cutting back hours.

The company isn't necessarily alone in trimming its workweek, but the idea of doing so in spite of its goal to expand is new, and it speaks to how much the initiative to give workers time off (or similar benefits) is growing. Shake Shack is also providing general managers with $10,000 equity awards.

A financial services firm in New Zealand had a six-week trial in which 250 employees worked four days instead of five while being paid for five days. Workers were 20 percent more productive and showed a 24 percent improvement in work-life balance after downshifting to a 32-hour week, so the company has made the four-day option permanent. Shake Shack may be looking to do the same, and it wouldn't be the only one to do so in the near future.