What's not to like? Plenty, says James Sherk, senior labor economics analyst for The Heritage Foundation in Washington, D.C.

"Shorter workweeks will make it harder for low-income Americans to get ahead," he says. "Workers with full-time schedules earn raises and promotions more rapidly than part-time workers. Reduced hours mean workers take longer to gain experience — and the higher pay that comes with it."

Ongoing debate

Love them or hate them, short workweeks have been a popular discussion topic since Slim raised the idea. However, this concept is nothing new. As far back as the 1930s, economist John Maynard Keynes predicted 15-hour workweeks by 2030. And in the early 1970s, the United Kingdom mandated three-day workweeks to conserve energy during a strike by coalminers.

Reducing time on the job may be a tough sell for Americans, who work an average of 1,790 hours a year, compared with a Western low of 1,397 for Germans. Proponents point to a 2013 study in the American Journal of Epidemiology showing that "a combination of stress, raised blood pressure and unhealthy diets stemming from long working hours may be the cause of thousands of workers' serious health problems."

The progressive New Economics Foundation in London identifies potential 10 benefits from a 30-hour workweek, along with its reasoning:

• Smaller carbon footprint. Countries with shorter average hours tend to have a smaller ecological footprint, according to the foundation.
• Stronger economy. If handled properly, a move toward a shorter workweek would improve social and economic equality, easing dependence on debt-fuelled growth.
• Better employees. Those who work less tend to be more productive per hour than those regularly pushing themselves beyond 40 hours.
• Lower unemployment. A shorter workweek would help redistribute paid and unpaid time more evenly across the population.
• Improved well-being. Giving employees more time to spend as they choose would greatly reduce stress levels and improve overall well-being, as well as mental and physical health.
• More equality between men and women. Moving toward a shorter workweek would help change attitudes about gender roles; promote more-equal shares of paid and unpaid work; and help revalue jobs traditionally associated with women. 
• Higher-quality, affordable childcare. Besides bringing down the cost of childcare, working fewer hours would give parents more time to spend with their children.
• More time for families, friends and neighbors. Spending less time in paid work would enable people to spend more time with and care for each other.
• Making more of later life. A shorter and more flexible working week could make the transition from employment to retirement much smoother, spread over a longer period of time. People could reduce their hours gradually over a decade or more.
• Stronger democracy. People would have more time to participate in local activities, to find out what's going on around them, to engage in politics, locally and nationally, to ask questions and to campaign for change.

Looking at the downside

Not so fast, says Sherk of the Heritage Foundation. The shrinking of the workweek already has begun, he says, and not necessarily by design.

"For employees in the bottom quintile, the average workweek has shrunk by more than an hour since the recession began," Sherk says. "The proportion of workers in the bottom quintile with full-time jobs also dropped significantly. In some industries and occupations, the decline amounts to losing five weeks of work a year."

Three-day workweeks, which may be appealing to salaried employees, can take a bite out of the income of hourly workers.

"These shrinking workweeks have particularly hurt the most vulnerable by cutting their take-home pay," he says. "Shorter hours mean the average worker in the bottom quintile takes home almost $500 a year less. In discussing income inequality, pundits often overlook hours inequality: those in the top quintile make more in part because they work much longer hours than those in the bottom."

Sherk expects full implementation of the Patient Protection and Affordable Care Act to exacerbate problems.

"PPACA penalties will raise the average cost of hiring workers in the bottom quintile by one-sixth — if they work full time," he says. "However, businesses can avoid these costs by cutting workers' hours to part-time. Polling shows a third of franchised businesses (such as fast- food restaurants) have responded to Obamacare by cutting hours. That figure will only rise when the penalties kick in next year."

Others may reduce their hours by choice.

"Employees generally work full-time for two reasons: to make more money and to get health benefits," Sherk says. "Under PPACA, the government now subsidizes health benefits, but only for workers whose employers do not offer it. Many workers can now make as much working part-time without health benefits, taking all their compensation in cash and collecting exchange subsidies, as they would by working full-time and taking part of their compensation as employer-provided health coverage."

Sherk, like Slim, foresees shorter workweeks in the future but for different reasons.         

"Obamacare will put downward pressure on both the supply of and demand for full-time jobs," he says. "The Congressional Budget Office estimates PPACA will appreciably shrink total hours worked in the economy over the next decade, finding the largest declines will probably occur among lower-wage workers."

American workers, with a strong work ethic, fresh off a recession and still uncertain about the future, are unlikely to demand three-day workweeks any time soon. What surveys say they want most — and what many employees are delivering — is greater flexibility and improved work-life balance. Businesses that find this middle ground are likely be the ones that succeed in employee satisfaction and retention.

Also read:

• Employees clamoring for workplace flexibility
• Top 10 jobs for work-life balance