If you're still deciding whether you should trial a 4-day week, it can be helpful think about it using a framework described by former poker champion and decision scientist Annie Duke in a January 2025 Washington Post op-ed.

First, think about a 2 x 2 matrix consisting of two choices, and two outcomes. The choices in Duke's case were take a buyout and early retirement or not; the outcomes were either happy or sad.

In our case, the choices are implement a 4-day week, or continue with business as usual (the two rows).

The two outcomes (the columns) as either good or bad: the 4-day week has either succeeded and addressed your organization's challenges, or it has failed.

In order to figure out out which choice is most preferable, Duke suggests the following process.

"1. Picture yourself a year from now under four scenarios, where you are either unhappy or happy. Here happy means the sense you are achieving your goals and living a life that aligns with your values. Assign a probability to each."

This might feel a little strange, but she says, "In my experience, people tend to balk at putting a probability against scenarios such as these. After all, we can’t know what the chances are." However, any "decision about which path to take is a guess about which path will make you the happiest in the future. It’s better to make that guess explicit."

Note that the probabilities have to add up to 100%: if you think there's a 80% chance that a 4-day week would succeed, then there's a 20% change it would fail. Likewise, an 80% chance that a 4-day week would succeed implies a 20% that business as usual would succeed-- and thus an 80% chance that business as usual would fail.

Early-adopter organizations were almost all inspired to try a 4-day week by a crisis that signaled it the organization would fail unless it changed how it worked. Losing several key people, or a personal crisis for the founder, or a high degree of burnout, all are easily signals that the organization needs to change. Put in 2x2 percentages, these organizations estimated that the odds of failure with business as usual were approaching 100%. This left them with little choice but to change things up.

More recently, some organizations have felt themselves in less dire circumstances, but the 4-day week is still attractive as a way to solve several problems they’re facing at once: to boost recruitment, improve retention, and create more space for deep work or thinking, for example. And a few organizations have treated the 4-day week as one option among several: they’re experimenting with hybrid and flexible work, and want to figure out which offers the best outcomes.

If one choice isn't a clear favorite-- if your estimations are close to 50-50, in other words-- keep going.

"2. Take a deeper dive by doing a “premortem," an exercise where you imagine a future where things have gone poorly and you explore how you got to there. Then try a “backcast,” an exercise to unpack why things went well. These can help offer clarity on which path is better for you in the long run."

In a premortem, Duke recommends you imagine that there were "early signals that things were going to turn out poorly" in a failure, as well as easy signals that it would turn out well. In a 4-day week, early signals of failure might be strong resistance among employees, problems meeting deadlines, a drop in revenues, or a drop in NPS score.

Then, do a backcast: think about the signals that you're going to succeed-- say, larger-than-expected efficiency gains, skeptics becoming enthusiasts, or NPS scores going up. If some of these signals seem a lot easier to envision (or you're already seeing them now), that could be a sign that one path is preferable.

"3. When trying to decide between two paths, it is helpful to consider which is more likely to expand your opportunities. Having more options is a form of wealth, so the number of opportunities each path opens up to you should factor into your decision."

It's obvious which option will generate more free time for everyone, which is a big reason for choosing a 4-day week. But you might also ask whether it will create more options in your choice of future employees (hiring and retention), future clients (reputation), your ability to survive a crisis (resilience or capacity), your ability to change how you work (a smarter, more technically-savvy workforce, better culture), or your bottom line (revenues, cash reserves).

Duke has several more steps, but these will probably be enough to clarify your choices. Of course, in order to accurately estimate your odds, and think through the early signals of failure and success, you need to be well-informed about how the 4-day week works, what organization do to make it work, and what benefits they see. Taking a look at my book Shorter: Work Less, Do More--Here's How, or our list of first-hand accounts of 4-day week companies, or the research reports published by 4 Day Week Global, can bring you up to speed.