At 11 a.m. on Friday, Mark Mullen, the CEO of Atom Bank, answered a call from The Sunday Times while shopping in a supermarket.

Three years ago, Mullen implemented a four-day work week for Atom Bank’s 550 employees, transitioning from a traditional five-day schedule. Now, with his Monday to Thursday work completed, he’s running errands such as grocery shopping.

According to Mullen, this shift has proven successful. He states, “We’re profitable, still growing—but we do it with a four-day week.”

The UK government is considering similar flexibility for workers, with a proposal for a system of “compressed hours” expected to be consulted on this October. This would allow full-time employees to complete their hours over four days instead of five, with employers legally required to accommodate such requests.

The aim is to enhance employee flexibility, allowing adjustments to workdays or hours which could include evening shifts.

This move isn’t unique to the UK; Belgium enacted similar legislation in 2022, with trials also conducted in various European countries. However, questions remain regarding the practicality and potential impact of a condensed work schedule on businesses and the broader economy.

A comprehensive trial last year, involving 61 companies that adopted the four-day week, indicated positive outcomes for employees, including decreased stress levels and fewer sick days.

Nevertheless, Mullen cautioned that a four-day work week might not suit every business model. He emphasized that Atom Bank’s operations are “self-service, digitally enabled,” which makes a condensed week more feasible than for industries reliant on physical services, such as restaurants.

Atom Bank reduced its contracted hours from 37 to 34 per week, requiring employees to work slightly longer days but without a decrease in wages. Mullen reports, “It had no impact on [total] productivity at all,” though productivity per hour improved.

Professor Bart van Ark of the Productivity Institute at Manchester University cautions that while some may thrive with longer hours over fewer days, it can lead to fatigue and decreased concentration. He notes that productivity tends to wane after seven or eight hours of work per day.

Richard Fox, a partner at Keystone Law, also highlighted the complexities of implementing a four-day work week. Working ten-hour shifts over four days can lead to exhaustion, suggesting steadier hours may be preferable for some.

Mullen acknowledged that not every employee may prefer a condensed work schedule, stating, “Some people like a five-day week.” However, he pointed out that once adopted, many employees find it difficult to return to a five-day schedule, which could create challenges for companies trying to attract new talent.

After last year’s trial, 92% of the participating companies opted to make the four-day week permanent, although some faced difficulties. Mark Roderick, managing director of Allcap, an engineering firm, noted challenges in coordinating staffing and customer service due to the new schedules. Allcap ultimately abandoned its trial after employees reported exhaustion from working nine long days over two weeks.

Asda also halted a pilot project for its store managers, who found eleven-hour shifts too taxing, resulting in fatigue on their extra day off.

Abigail Marks, a professor at Newcastle University Business School, warned that the four-day week might not be beneficial for all workers. For those in gig economy roles, such as Deliveroo drivers, the condensed schedule does not address the unique challenges they face. Many employees have reported needing to work on their days off to keep up with their tasks.

While companies like Atom Bank have successfully transitioned to a four-day week, such changes remain infrequent at a national level. Belgium’s new legislation, which allows workers to request a compressed work week, began in November.

Early indicators suggest limited engagement with the new option in Belgium, with only 0.8% of full-time workers utilizing the arrangement in an April survey. This may be attributed to the fact that the average working week for full-time employees in Belgium is already one of the shortest in Europe, averaging 34.9 hours.

Countries like the Netherlands, which has an average work week of 32.2 hours, have not enforced a four-day work week, although part-time employment is notably popular. Despite a shorter work week, the Dutch exhibit high productivity levels, clocking in an output of €53,000 per capita, significantly surpassing the UK’s roughly €39,000.

Germany, the lowest among the top five European economies, records 34 hours per week on average, supported by high automation levels in manufacturing. Germany is noted for its work ethic but typically does not exceed seven or eight hours in a day.

This year, Germany’s GDP per capita is projected to be around €39,000, influenced by disparities in productivity across regions.

In contrast to the UK’s consideration of a four-day work week, Greece has moved to allow a six-day work week. Under prime minister Kyriakos Mitsotakis, since July 1, companies in select sectors may require staff to work six days a week in exchange for 40% additional pay for the extra hours. This measure targets the private sector, specifically in industries operating continuously.

The food and tourism sectors were exempt from this rule due to pre-existing authorizations for additional workdays. Unions contend that Greece’s shift diverges from broader European trends, but Mitsotakis defends the policy as necessary for addressing a labor shortage worsened by a significant population decline since the 2010 debt crisis.

Greece’s workforce already faces the longest hours among major European nations, averaging 40-hour work weeks and struggling with low wages.

For companies transitioning to a four-day work week, careful planning is essential. Alice Lang, 30, from Chester’s Marketing Signals, described her agency’s solution by implementing alternating teams to ensure coverage throughout the week. She noted that, since this change, her work-life balance has significantly improved, with increased productivity and reduced stress levels, as she now manages her tasks more effectively and enjoys longer weekends.