The results of the recent 4-day week pilot are interesting.
www.4dayweek.co.uk
That all seems fairly positive to me.
If they're achieving 5 days work in 4, and potentially getting more done in that time, and being paid the same, what on earth is wrong with it? The employer isn't losing out and staff are healthier and happier as a result; it's a win-win for everyone. It should be a surprise to nobody that workers who don't feel burned out are better at their jobs, are less likely to quit and less likely to go off sick. It doesn't necessarily mean a 3 day weekend, either; it's perfectly feasible to have that extra day through the week.