There were some fairly major studies in the UK last year, across many companies and multiple industries, where they reduced the 5 day workweek to a 4 day workweek, whilst keeping the compensation of workers the same overall (i.e. salaried workers got the same salary, hourly workers got 25% more per hour)

The majority of companies involved in the study found that their workers were significantly healthier and happier after adjusting to the new schedule... and as a result significantly more "productive". Profits even went up despite the reduced working time. Most of them elected to keep with the new system once the study ended.

Obviously you can't do this with every industry, certain industries need 24/7 coverage or the like... you can't run an ER 4 days out of 7 - but the takeaway is that it'd be better to employ more people for less time and pay them well - you'll get better results than you will with an exhausted and depressed workforce