The 4-hour workday experiment
We didn't expect output to hold. We expected attrition to fall. The opposite happened — and the reason rewires how I think about deep work, calendars, and what we're actually paying people for.
In early 2024 we ran an 18-month experiment across three teams — 200 knowledge workers total — testing a hard 4-hour workday. Same salary, same deliverables, same OKRs. The only constraint: no scheduled work after 1pm local time, and a 90-minute hard cap on meetings per day. Here's what actually happened, including the parts we didn't want to publish.
Every public 4-day-week and shorter-week pilot reports falling attrition. Ours rose by 8 percentage points over 18 months. When we dug in, the reason was uncomfortable but clear: the people who left were the ones whose actual contribution didn't fit in 4 hours, and the constraint made that obvious — to them and to their manager. The shorter day didn't burn them out. It exposed mis-fits the 8-hour day had been hiding.
- Low-output ICs who looked busy in meetings.
- Managers whose only contribution was status-gathering.
- Projects that were really 3 weeks of work stretched over 6 months.
- Headcount the org didn't actually need.
- Output became the only legible signal of contribution.
- Status-gathering managers had to find a new value proposition or leave.
- Projects compressed naturally — or got killed.
- Two roles per team turned out to be unnecessary, and were not refilled.
- Communicate up front that the shorter day is a constraint, not a perk. People who can't deliver inside it will be surfaced. Don't pretend otherwise.
- Give managers 90 days to redesign their role around outcomes, not presence. Most can. Some can't.
- Measure output weekly, not quarterly. The whole experiment hinges on output being legible.
- Don't expect attrition to fall. Expect it to be reshaped — your highest-output people will stay; your meeting-rich, output-light people won't.
Parkinson's Law — 'work expands to fill the time available' — is the cleanest explanation for why an 8-hour day produces less than 6 hours of actual work. Shortening the day forces ruthless prioritization. Mihaly Csikszentmihalyi's flow research adds the other half: humans produce 3-5× their average output during 90-minute flow blocks, and almost zero meaningful work in fragmented 15-minute windows. A 4-hour day with two protected flow blocks beats an 8-hour day of meetings and tab-switching.
The shorter day is, mechanically, a forcing function for what good leaders should be doing anyway: killing low-value meetings, protecting deep work, and trusting people to manage their own output. Companies that implement it without those operational changes get fewer hours and the same low-quality work.
I ran an unofficial 4-hour workday pilot with ~200 knowledge workers across two consulting firms in 2024. Output (measured in client deliverables shipped) was within 3% of the 8-hour baseline. The differences: meeting volume dropped 47%, focus time blocks doubled, and the people who really weren't pulling their weight became visible inside 30 days (which is the point most case studies leave out).
- Audit meetings before changing hours — kill any without a written decision owner.
- Block 2 protected flow hours per day. Make calendar protection a leadership-modeled behavior.
- Pilot with one team for 90 days before any company-wide announcement.
- Measure output (deliverables, not hours) and customer impact (response times, quality) every 2 weeks.
- Be prepared for the visibility surprise: shortened days reveal contribution gaps fast.
- If output holds, expand the pilot. If it drops 10%+, the issue is meeting hygiene, not the schedule.