The four-day workweek is gaining ground in Europe. It’s time Americans give it a serious look.

With the “Great Resignation” still in full-swing, and work-induced burnout an official occupational hazard according to the World Health Organization, a growing number of employers — and countries — are rethinking the standard 40-hour workweek. Iceland led the way in experimenting with shorter workweeks, without pay cuts, over several years. The experiment has largely been hailed as a success, with an estimated 86 percent of workers expected to adopt it.

Now Belgium has announced it will allow workers to request permission to compress their work hours into four days. Companies in North America are following suit; a coalition of U.K. companies is expected to replicate the experiment this summer. In the United States, U.S. Rep. Mark Takano (D-Calif.) has proposed a bill that would reduce all standard workweeks to 32 hours, requiring overtime pay for anyone working beyond that.

Perhaps the biggest argument in favor of a shorter workweek is that it doesn’t seem to harm productivity, counterintuitive as that may seem. Part of this is due to the human tendency to stretch or condense the time needed to complete a task based on the time we have available. If we know we have eight hours to fill, we’ll pace ourselves; the promise of an earlier quitting time provides incentive to buckle down and streamline our work habits.

The other part is that minds and muscles can function for only so long before fatigue kicks in and starts affecting long-term health. After a certain length of time, most workers start getting diminishing returns on their efforts. After 50 hours in a week, stress-induced damage starts appearing in the form of high blood pressure, irregular heartbeats, insulin resistance, and other dangerous symptoms.

And some kinds of work are best done in sprints of less than eight hours a day. Research has found that for tasks requiring sustained deep concentration and a state of “flow,” more time does not produce deeper or better-quality thinking. For those kinds of jobs, six-hour shifts may be optimal.

Working fewer hours per day would bring many parents’ schedules more in sync with those of their school-age children, giving parents opportunities to be more present and less exhausted during family time.

Overall, four days’ labor, three days’ leisure seems more balanced than the prevailing five-and-two model.

But, of course, shorter workweeks have their downside.

They don’t work equally well for all jobs. For task-based work, the amount of time you spend shouldn’t matter as long as the work is finished and is up to standard. For jobs that revolve around client schedules, timed processes or billable hours, however, there’s no way to reduce work time without affecting output and profitability.

They could put colleagues out of sync with one another. Workers clearing their desk so they can bolt have little incentive to support their colleagues. That can foster resentment, whereas shared workloads can boost camaraderie. Also, down-time is often when bonding and socialization occurs at the workplace.

Compressing five eight-hour days into four days of 10-hour shifts, as Belgium is doing, may not help with stress, even if it results in a three-day weekend. As noted above, productivity and quality, not to mention worker health, may suffer during those longer individual shifts.

Shorter workweeks won’t help workplaces that are already running lean. One of the causes of the “Great Resignation” is that workplaces have made workers do more with less for too long. A workplace that is chronically under-resourced and overloaded would have to add staff or cut back on projects and expectations to make a shorter workweek possible.

Finally, there will always be exceptions. Whether through legal carveouts, such as the 7(k) work period rule that essentially moves the overtime goal posts for emergency workers, or FLSA-exempt status that allows employers to pay for 40 hours even when workers are giving more, the 40-hour week isn’t consistently and equitably applied. There’s no reason to expect that a shorter workweek would be, either. And as with income distribution, those in greatest need would probably be least likely to be allowed to enjoy the benefits of a shortened workweek.

Despite those concerns, it’s clear we need to rethink how we allocate our time, individually and as a society. When it was first implemented, the 40-hour workweek was a huge improvement over the 80- to 100-hour weeks people had been working before — the “work until you drop dead in your shoes” school of management. But now, after decades of increased automation and innovations that let us work ever more efficiently, why are we still trying to wedge more productivity into the time we’ve supposedly saved?