One proposal has been to go to an 8-day week with a 3-day weekend. This only reduces worked days by 12%, instead of 20%.
Then someone named "Domingo" (Spanish for sunday) call them "guys, you are the inventors of Osvaldo" and tell the history of a group of friends inventing Sunday. It was very funny.
Couldn't find a best resolution:
A 6 day week, 4 days on, 2 days off would be much easier to devise a calendar for I think.