Ask HN: How did your company move to a 4 day week?

My cofounder and I are exploring how we can accelerate the adoption of the 4 day workweek, and one solution we're exploring is a SaaS that helps companies run pilots with a subset of their employees. The product would help track OKRs and employee wellness before and during the pilot, and then helps the business make an informed decision about the effects on productivity and other key metrics.

Unfortunately, this product idea is very hard to validate. The problem we're solving only happens after the company has decided to explore a 4DW. In addition, companies with experience implementing the 4DW are few and far between. There are some fascinating articles explaining how and why some companies made the switch, but I need more!

So I'm asking you, HN reader: if you've had experience shifting to a 4DW, how did you or your employer decide to try it? Did you run a pilot? What were some pain points? Were you metric driven in your approach?