A walk through the big four-day week pilots in Iceland, the UK, Portugal, Germany and Spain, and the largest scientific study so far. Wellbeing results point the same way, while the evidence on output is thin, and the hosts explain why the headline numbers are both more and less convincing than they look.

Mia and Adam are AI voices. Walking Points is made by AI from the sources cited in this description. Its facts are checked by AI against those sources before release, and a person approves every public part before it goes out.

This part was made in September 2026.

0:00 Two revenue numbers, one trial
0:19 What a four-day week trial is, and what it is trying to prove
3:01 Iceland, 2015 to 2019: The trial that started the story
5:12 The UK pilot, 2022: The one behind most headlines
6:36 Portugal and Germany: Pilots with a comparison group
9:10 Spain: The trial that mostly did not happen
9:54 The biggest paper: Nature Human Behaviour, 2025
11:50 One month at Microsoft Japan: The number everyone quotes
12:17 What the trials measured, and what they did not
13:12 Why the headline numbers are more convincing than they look
13:42 Why they are less convincing than they look
15:01 What this changes for someone reading the next headline

The Four-Day Week and Other Experiments, part 1 of 3.
Next in this series: Part 2, Where the four-day week breaks.

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Sources:
Autonomy Institute: Going Public: Iceland's Journey to a Shorter Working Week https://autonomy.work/portfolio/icelandsww/
The Conversation (Anthony Veal): The success of Iceland's 'four-day week' trial has been greatly overstated https://theconversation.com/the-success-of-icelands-four-day-week-trial-has-been-greatly-overstated-164083
Autonomy Institute: The results are in: the UK's four-day week pilot https://autonomy.work/portfolio/uk4dwpilotresults/
The Conversation (Anthony Veal): 4-day work week trials have been labelled a 'resounding success'. But 4 big questions need answers https://theconversation.com/4-day-work-week-trials-have-been-labelled-a-resounding-success-but-4-big-questions-need-answers-201476
Henley Business School: Results from Portugal's government-backed 4-day week trial released https://www.henley.ac.uk/news/2024/results-from-portugals-government-backed-4-day-week-trial-released
Phys.org (University of Münster): Well-being increases when working hours are reduced, finds Germany-wide study https://phys.org/news/2024-10-hours-germany-wide.html
idealista/news: Spain's Valencia tests the four-day working week https://www.idealista.com/en/news/lifestyle-in-spain/2023/04/26/120089-valencia-makes-the-most-of-public-holidays-to-test-the-four-day-working-week
Catalan News: Congress rejects reducing workweek to 37.5 hours https://www.catalannews.com/politics/item/congress-vote-working-week-375-hours-10-september-2025
Nature Human Behaviour (Fan and Schor): Work time reduction via a 4-day workweek finds improvements in workers' well-being https://www.nature.com/articles/s41562-025-02259-6
Scientific American: Biggest trial of four-day workweek finds workers are happier and feel just as productive https://www.scientificamerican.com/article/biggest-trial-of-four-day-workweek-finds-workers-are-happier-and-feel-just/
Autonomy Institute: Critics of shorter working week trials consistently miss the mark https://autonomy.work/portfolio/critics-of-shorter-working-week-trials-consistently-miss-the-mark/
CNBC: Microsoft Japan's 4-day workweek experiment sees productivity jump 40% https://www.cnbc.com/2019/11/04/microsoft-japan-4-day-work-week-experiment-sees-productivity-jump-40percent.html