Flexible schedules free workers from rigid hours, boosting their health and productivity. Or they kill collaboration.

It depends on who you ask.

Some business leaders bill the workplace policy as a panacea for working parents. Why take a day off when your child has the flu if you have a laptop? Others — perhaps most famously, Yahoo’s Marissa Mayer — say staffers working at different times and locations cramps quality. “To become the absolute best place to work, communication and collaboration will be important, so we need to be working side-by-side,” Yahoo told its employees in a 2013 memo that prohibited them from working from home.

Heejung Chung, a sociologist at the University of Kent in England, recently drove the discussion further, bolstering the idea that employees who work from home put in longer hours — though no one can definitively say whether that labor is better or worse.

In the study, published this month in the European Sociological Review, Chung's team examined the work habits of German employees with flexible work hours from 2003 to 2011 and found they bagged more overtime pay than those in stricter arrangements. That pattern held true regardless of position or type of job.

Chung found that men and women in full-time jobs with flexible schedules worked about the same amount of overtime hours. The same went for mothers and fathers.

The men, however, saw an earnings increase beyond overtime pay after switching from a concrete schedule to flexible hours. They banked an average of 1,000 more euros (about $1,125) per year. The women enjoyed no such gains.

 Predicted overtime with fixed schedules, employer flexibility, and working-time autonomy for men and women in full-time positions.
Image: Lott and Chung, European Sociological Review

“Employers tend to believe that women use flexibility mainly for family-friendly purposes, which results in women not being rewarded in the same way as men when using flexibility," Chung wrote last week, "regardless of the increase in their devotion to work they exhibit.”

The report carries relevance in the United States, where the time Americans spend at work has increased sharply over the past four decades. The average worker amasses 1,836 hours per year, up 9 percent from 1,687 in 1979, according to the Economic Policy Institute. The trend probably stems from technological advances: omnipresent smartphones, video chat, Google docs. (Note lower-paying jobs and work that involves physical labor are less likely to accommodate flexible schedules.)

Meanwhile, about three-quarters of U.S. firms now allow some kind of scheduling flexibility, government data show.

Researchers warn a rise in flexible work will not level the playing field for working parents, particularly mothers, if bosses cling to old stereotypes about primary caregivers. A study last year from the Harvard Business School found women were judged more harshly for leaving the office early.

German women, like American women, still shoulder the majority of domestic responsibilities. Chung’s research suggests what a large body of academic evidence already supports: Mothers are sometimes viewed as less committed employees, regardless of their productivity — and that perception appears to show up in the way they are paid.

A Third Way study this year found fatherhood on average brings a 6 percent wage boost for each child, while motherhood is associated with a 4 percent pay penalty.

"Greater flexibility and autonomy over work sound great — and could well herald a new era of better work-life balance," Chung wrote. "But … we need to better understand exactly what’s going on to tackle some of these negative consequences."