It seems to be a success among companies in the U.K. that started a pilot program earlier this year. Instead of five 8-hour days, people are working four 10-hour days. So far, none of the companies have recorded a drop in productivity and some have seen an increase.
Personally, I'd be more than happy to make that transition. It's the same amount of working hours so companies would not lose anything and we would be getting three full days for ourselves and our families a week. That would be a dream come true. I would even be willing to RTO for that.