Four-day week trial confirms working less increases wellbeing and productivity

The title claims that a four-day week trail shows that working less increases productivity.

The article provides two data points for this.

1) The author's personal research, in which they say they measured a 10% increase in productivity, but about which they explicitly fully admit that in the end it doesn't make up for the loss of productivity from working 20% less. They actually write in the article that end productivity would be less.

2) They link to a study of a single Japanese company that was overworking their workers by 20-40 hours of overtime each month, which was reduced to ~20 hours of overtime after the 08 recession. They took the income the employees earned, divided it by how many hours they worked, and somehow determined that the employees were "7.6%" more productive when they had to work less overtime. This study has nothing to do with a four-day work week, it's for a single company, and for a company that was already working their employees well past a normal 40 hour work week.

That's it. That's the proof they provide, as they make the claim that four-day work weeks increase productivity. One data point that the author admits doesn't say that, and one data point that has nothing to do with a four-day work week and makes little sense.

This type of research is guaranteed to obtain (and report) the results they want to see ahead of time. Can you imagine a title "four-day week trial reports reduced productivity" ?