It seems... rather too convenient that a 20% work reduction would produce a 25% increase in productivity for a nice neutral result. I don't doubt that working fewer hours improves productivity, but do we really expect the two to line up so neatly? I've seen two explanations for this, but neither really satisfies.
Claim one is that time off recharges and focuses us. We get more sleep, are less distracted by outside tasks (e.g. calling a doctor who's only open during work hours), burn out less, and still get the full benefit of outside-work productivity like having a new product idea at 10PM. Some parts of this make sense; outside-work insights still progress at seven days per week, and an hour off work for calls and errands is an hour that can be directly recovered. But the rest is puzzling; why should rest and recreation repay themselves so precisely in work output?
Claim two is that productivity isn't limited by office-time in the first place. A powerlifter who doubles their workout time won't see any benefit because they're hitting physical limits already. This makes much more sense; we've all had experiences like struggling with a problem that looks obvious the next morning, or sitting around unproductive because our most urgent work is blocked by some external factor. But again, the shape of the result is surprising; surely not all of that lost time is recovered by taking time off. Mental fatigue would be better answered with 6-hour workdays, and some of those external blockers are always going to be unpredictable and unscheduled.
There are a few other views that make more sense, but are rather less promising. The article mentions that other companies trying this see a productivity spike and then lag, which could imply it's just a reaction to the novel approach. The discussion of productivity plans, and the interviewed employee who reduced multitasking, imply that this might just be a loss offset by other noncontingent process gains. (The matching result, then, presumably consists of people seeking process gains until the loss was offset.) The company could simply lack 40 hours/week of substantive work, which again could be cured with reduced hours or increased work.
Or perhaps employees were output-limited not by mental fatigue but by, essentially, giving-a-shit. One of the big insights of productivity studies is that "can't do more" and "won't do more" aren't clearly distinct when you're relying on internal motivation; there's no clear way to say that "won't" is happening on a different, volitional layer. If people were working 40 hours a week with 25 hours of 'drive', constant productivity makes more sense.
> Measurement is also not incidental here. Measurablity changes everything. Once an employees job productivity is measurable, it can be optimized and already has been.
And then there's this, yes. Uncomfortably often, Taylorism isn't about process improvements but squeezing relaxation and well-being out of a job. If you can't measure productivity well externally, then a move like this might get employees to 'Taylorize' themselves because the harder work will be offset by the wellbeing from more time off. If you can, then they'll get Taylorized from the outside, and the offset will tend to be higher wages or nothing at all.