My point is that the situation you're envisioning is unrealistic. If you only work 4 days then you won't make enough money to afford the kind of lifestyle that you likely want.
Is it unrealistic to move from working 6 days to 5 days a week? Why was that possible, but 4 days isn't, even though productivity has increased?
What if companies are forced to pay the same? Why assume that that the state of the world when you were born is the only state possible?
And personally (which I'm not claiming is normal) my main issue in terms of money is not having a house. Otherwise, my issue is not having time to enjoy what I already have.
You say that the 5 day work week is "not fortunate". I say that I'm grateful to work 5 days a week.
Would you be grateful to have to work 6 or 7 days a week because that's the system? If you like 5 days, is that because you've been brainwashed to accept that, because that's the age you life in?
From a Christian perspective the work week was designed by God in the very beginning and is part of the fabric of creation. So it's not arbitrary. If it is violated then mankind will suffer.
In the original context wherein the Sabbath command was given people worked every day. It was an issue of faith to cease working for one day in order to quietly enjoy the work of God and trust that he provides for our needs.
It's seems arguing with a God opinion is pointless, but I'm not sure theologically your point stands up. (eg: 'God commanded' doesn't mean not arbitrary; and I don't remember a penalty in the Bible for working less days).
Anyway, original people lived in different times, what was necessary for them doesn't have to be necessary and good for us. My understanding is that nomads may have only worked 18 hours a day. Working 3 hours a day also doesn't seem so bad.
Ok. It's easy to oppose something or to complain about the current "system". After all, what is crooked cannot be made straight and what is lacking cannot be counted (Ecclesiastes 1:15). It's much more difficult to propose a viable solution. So what do you think should be done? Are you really going to go to your employer and demand that he/she pay you the same wages for one less day of work?
It's also easy to say things should stay the same.
I propose we vote for a party in government that will change things. Perhaps all companies should be democratic, so the employees decide policies (enforce my law for medium and large companies).
Maybe requiring people to work 5 days a week should be illegal (along with raising the minimum wage; or low wages should be connected to high wages, so one cant raise or lower without the other). Maybe bank holidays should be expanded until the take up 1/7 of all weeks.
Anyway, there's a good chance robots and AI will take our jobs. Maybe we should accept that and move on and work to live, rather than live to work?