The reality is that as humans produce more technology these things will lessen naturally:
In essence more jobs with specialists will be born and fewer hours are required for those specialists to function in a manner that is appropriate to the task. What this basically translates to in laymen's is:
There are certain industries where a 3-day work week already occurs. In particular, many nurses in the health care industry will work three 12-hour shifts to fulfill their regular obligations. Of course, many will work more hours than that. The likeliest scenario though, is that companies will cut people to 3-day work weeks, while reducing pay and benefits as well. Capitalism will always work for the benefit of the mighty.
What benefit does a 3 day workweek give? Simple. Three days to earn money, four days to do nothing except procrastinate and put off the opportunity to learn how to better your skills and work your way up in the food-chain. This is simple.
By working 5 days, 11 hours per day, and cutting spending, a person can save enough to start his own home business, and perhaps fewer hours are necessary should they have a credit rating. The objective of massive corporate emperors, such as Carlos Slim (the man who recently popularized this dreadful idea) seek only to cut down on their competition, and to maximize the control they have over the markets in which they inhabit.
What are the benefits of a 3 day work week for ordinary humans? People will make less money, which would supposedly cut down on national inflation. People will have more "time with families" which you won't be able to enjoy because you can't afford anything.
What are the benefits of a 3 day work week for men like Slim? People will become too lazy to apply themselves, no longer getting into a position to maintain their own businesses. With less money in flow, the economy will begin to stabilize, but guess who still makes money? Silm. So, his net worth increase, and the dollar value for that net worth increases at the same rate, which makes him three times as wealthy.
So all in all, we don't need a decrease in work days. We need a decrease in population and the one-sidedness of corporate power over the common business. That can only be achieve through dismantling or out-competing it, locally.
The three day work week would not work well. It would hurt those who work by the hour as they would not be able to get in 40 hours and would have to take a second job which would negate the whole three day work week. Salary employees would have a hard time making up any time difference due to sickness. Also a lot can happen in four days and would not work for a person to be off four days in a row.
I don't believe that a 3-day work week will ever happen because our society has been programmed to work, in a normal scenario, 5 days a week. I think changing to a 3-day work week, but working longer hours would be a hard thing for everyone involved to adjust to.
No I definitely do not think that a three day work week will ever happen. Just to think of doctors trying to cram all of their patients into three days in unfathomable. Also to think of all the hospital emergencies that happen every single day. Also the stores that would be closed.