The Four-Day Work Week: Who Has Stuck With It and Who Reverted

It’s incredible really that around 2.7 million people in the UK now work a four-day week, roughly one in nine of the workforce. And that’s just the UK too. This is a look under the bonnet of the companies around the world really making it work. The 4 day work week has moved from fringe experiment to mainstream policy in less than a decade. But while some companies are thriving and seeing a strong ROI, some companies have reverted back to 5 day weeks.

The Early Adopters of the Four-Day Work Week

I remember about 15 years ago when the early trials hit the news, and reports of the intention started to circulate to mixed reactions and quite a lot of split opinion. But these early trials laid the groundwork for everything we see today.

Between 2015 and 2019, Iceland ran public sector trials involving 2,500 workers. Participants moved to 35 to 36 hour weeks without any reduction in pay. Productivity remained high or improved across nearly every workplace. The Icelandic trials are often cited as the starting point for the modern 4 day work week movement.

In 2018, New Zealand trustee company Perpetual Guardian tested a 240 employee trial. Staff reported a 24 per cent improvement in work-life balance and a 7 percentage point drop in stress levels.

Microsoft Japan tested a similar model in 2019, giving staff every Friday off. Sales jumped by 40 per cent compared to the same month in the previous year.

Public sector bodies joined the movement later. South Cambridgeshire District Council launched a trial in 2023. By 2025, 21 of their 24 key performance indicators were maintained or improved, saving the council £399,000 annually. They made the policy permanent.

The People Making the Four-Day Work Week Work: Featured Case Study

But some companies are finding it so successful that they are sticking with it for the long run. Exos, a corporate wellness and leadership coaching firm, provides a clear blueprint for how to execute a reduced hours model successfully. Before implementation, employee burnout rates hovered at 70 per cent. That’s extortionate.

Leadership introduced a structured four-day work week alongside dedicated recovery practices known internally as You Do You Fridays. They audited every meeting on the corporate calendar, introduced daily microbreaks, and trained managers to manage workloads by output rather than hours logged.

Burnout dropped from 70 per cent down to 36 per cent. At the same time, Exos recorded a 211 per cent year-over-year increase in their sales pipeline. The Exos case study is one of the most compelling four day week examples available. They worked directly with researchers from the Wharton School to measure outcomes and track productivity metrics objectively.

The Broader Evidence: UK Pilots, South Korea, and Global Trials

The evidence base expanded significantly following large scale national pilots. The UK pilot in 2022 involved 61 companies and 2,900 workers. Ninety-two per cent of participating businesses continued with the schedule after the trial ended, and company revenue rose by 35 per cent on average compared to previous periods.

A follow up UK pilot in 2025 across 17 companies and 1,000 staff achieved a 100 per cent continuation rate.

Internationally, governments are stepping in. South Korea launched a state backed support programme in early 2026, with 224 companies joining in the first six months. Many of these firms paired reduced hours with AI assisted workflow redesign to maintain output.

In Germany, approximately 70 per cent of firms that tested reduced hours continue to operate some form of the model. However, many shifted away from the rigid four-day work week label toward flexible monthly targets that fit local operational needs better.

Where the Four-Day Work Week Didn’t Work and Why

Understanding failures matters just as much as celebrating successes. When reduced hours fail, the root cause usually sits in poor operational design or scaling friction.

Accounting and advisory firm Cooper Parry ended a three year trial in February 2026. Leadership found they could not apply the model fairly across all client facing teams as the business scaled rapidly. They transitioned to a more flexible 4.5 day structure instead.

Magyar Telekom concluded a 20-month trial in 2024. Their experience shows that a 4 day week trial requires careful departmental alignment. They found efficiency gains inconsistent across different departments. Collaborative scheduling proved too difficult to sustain without creating bottlenecks.

Retailers faced different hurdles. Morrisons encountered staff complaints regarding mandatory Saturday work adjustments. Asda struggled with physically exhausting 11 hour shift models that clashed with employee recovery needs.

In Australia, Launceston City Council faced public backlash over perceived reductions in service capacity during peak operational hours.

Strategic Learnings for HR Leaders on the Four-Day Work Week

Analysing the companies that succeeded alongside those that reverted reveals clear patterns that lead to this success. Organisations considering a four-day work week must apply five core insights.

1. Redesign, Not Compression

Successful companies do not cram five days of tasks into four days. They eliminate redundant meetings, automate administrative duties, and reallocate focus. Exos audited meetings thoroughly. South Cambridgeshire restructured key performance indicators around results. Without structural redesign, reduced hours simply accelerate burnout. Many organisations suffer from poor management structures, often leaving accidental managers unequipped to handle complex workflow changes. The successful companies tackled all these things head on.

2. Measure Everything From Day One

Data protects policy decisions. Exos partnered with academic researchers at Wharton. South Cambs tracked 24 specific metrics. Companies that abandoned trials usually lacked baseline data to justify the transition or diagnose friction points early. When communication breaks down, organisations frequently slip into toxic dynamics where employees feel micromanaged, mirroring the wider issues seen when dealing with a toxic boss. Having clear measurements in place helps clear communication and alignment when friction points arise.

3. Build Flexibility Into the Model

Not everyone will benefit from a blanket ‘Friday off’ decision. Exos utilised flexible recovery days, while firms that failed often imposed strict uniform rules across diverse departments. True operational agility requires trusting teams to manage their own delivery schedules without heavy handed oversight, moving away from old bureaucratic habits and toward modern great unbossing principles.

4. Start With a Pilot

Every enduring success story began small. Leadership teams must test hypotheses, measure team feedback, and refine operational workflows before making permanent commitments.

5. Match Model to Sector

The four-day week is not a one-size-fits-all solution. Knowledge intensive professional services and tech firms capture productivity gains much faster than shift based or customer facing environments. HR leaders must tailor the four-day work week to the exact nature of their workforce, their operational demands, and their existing culture.