It is the sharpest question a sceptic can ask, and the fairest one: if the work still gets done in four days, are people simply working faster for four? Sometimes the honest answer is yes — and where that is true, the model is borrowing its results from people’s health. A serious pilot measures intensity rather than arguing about it.
What intensification actually looks like
Intensification rarely announces itself. It looks like shorter lunches, meetings back-to-back with no thinking time between them, inboxes handled at midnight because the day off moved the deadline, and a low hum of “I can’t get sick this month.” Staff will often report it as pride at first — the team rose to the challenge. By month three, the same pattern reads differently in the sickness and resignation data.
The pilot evidence is reassuring but not a blank cheque. In the UK 2022 trial, reported stress fell for 39 percent of staff and burnout fell for 71 percent, which would be unlikely if four days of frantic work simply replaced five calmer ones. Portugal’s 2023 pilot, reported in December of that year, found the anxiety and fatigue indicators moving down within months. But those pilots paired the shorter week with deliberate work redesign — fewer meetings, dropped reports, changed processes. Where firms cut the day and changed nothing else, the workload had nowhere to go except into pace. That distinction, not the calendar, is what your intensity measures need to capture.
Three measures that tell the truth
Hours actually worked is the first. Compare timesheets, system logins and message timestamps before and during the pilot. If contracted hours fell twenty percent but actual hours fell five, the missing fifteen is intensification or hidden overtime, and the wellbeing scores will eventually say so.
Workload manageability is the second, and it needs a validated form of words rather than a home-made smiley scale. Ask, at baseline and monthly: can you complete your work within your hours, do you recover between working days, and how often do you work faster than feels sustainable? Track the subgroup answers — intensity concentrates in particular teams, grades and caring situations long before the average moves.
Meeting and message load is the third. Count meeting hours per person per week and after-hours messages. A common failure mode is meeting migration: five days of meetings compressed into four, leaving no focus time and pushing real work into evenings. If meeting hours did not fall during your preparation phase, they will not fall by themselves in the pilot.
The design choices that prevent the treadmill
Intensification is mostly a capacity problem, so the fixes are capacity fixes. A stop-doing list with named owners, agreed before launch, that removes at least a tenth of current activity. Meeting defaults cut to 25 or 30 minutes with agendas, so shorter time does not mean denser time. A workload triage conversation in every team in the first month: what is critical, what is customer-facing, what can wait, what dies. And an explicit intensity tripwire in the pilot terms — for example, if self-reported unsustainable pace rises for two consecutive months in a team, that team pauses and redesigns rather than pushing through to the decision date.
Leaders should expect an honest month-two conversation. Early enthusiasm carries many teams through the first weeks; the dip comes when novelty fades and the unreformed processes reassert themselves. That dip is data, not failure — provided you built the measures to see it and the authority to act on it mid-pilot.
Practical takeaways
- Measure actual hours, not contracted hours — the gap between them is your intensification.
- Survey manageability and pace monthly, and read the results by team, not just in aggregate.
- Count meeting hours and after-hours messages; watch for meetings migrating into fewer days.
- Prevent the treadmill with a stop-doing list, meeting defaults and workload triage before launch.
- Write an intensity tripwire into the trial terms so a struggling team redesigns early instead of quietly burning out.
Sources
- Autonomy, University of Cambridge and Boston College, UK four-day week pilot results, reported February 2023 — https://www.sciencedaily.com/releases/2023/02/230221113132.htm
- Portugal four-day week pilot, Birkbeck and Henley Business School, reported by Personnel Today, 14 December 2023 — https://www.personneltoday.com/hr/portugals-four-day-week-reduces-anxiety-and-fatigue/
- Autonomy, UK pilot one-year follow-up, reported February 2024 — https://www.hrdconnect.com/2024/02/26/one-year-on-uks-4-day-work-week-trial-has-been-a-success/
Day5Group is a consultancy that assists in the transition to a 4 day work week. More about Day5Group · All blog articles