From the article:
A closer look at the design of the study, however, might raise some doubt about how useful the findings are.
Two companies voluntarily dropped out in the course of the six months, and two others had to be excluded from the evaluation. Of the remaining 41 participating companies, only about a third reduced weekly working hours by an entire day.
Around 20% reduced hours by between 11% and 19% per day, while about half cut work time by less than 10%, or roughly four hours per week. So, in total only in 85% of the cases did employees get a full day off.
The limited number of participating companies also makes the study hardly representative of Germany and its more than 3 million registered firms. This has been because the project struggled to find enough interested employers since it was first mooted two years ago, said Marika Platz, because part-time work is already relatively common in Germany.
Labor market expert Enzo Weber is skeptical about the pilot project, saying that companies participating in such trials are generally already positive toward the 4-day workweek, making them an unrepresentative sample of the economy.
In addition, the researcher at the University of Regensburg and the Institute for Employment Research in Germany, told DW the project's productivity gains may not be due to shorter hours alone, as processes and organizational structures were also modified.
Weber also believes the positive results might not be sustainable due to the increased work compression that will likely come at the expense of employees' social, communicative, and creative aspects. "The effects often don't manifest immediately but rather in the medium term," Weber said, noting that those studies generally cover only a relatively short period of six months.
According to Steffen Kampeter, CEO of Germany's Employers Association BDA, companies that operate in international markets consciously chose not to participate in the trial. He also questions the productivity gains, arguing that "a four-day week with full pay is just a significant wage increase, which most companies cannot afford."
