It's interesting that people are not considering the business point of view...
I read some people mentioning about working 10-hours a day and work from Monday to Thursday. If I was a business owner I wouldn't allow that. I would rather offer 5~6 hours work per day than allow him to work more for 4 days.
In my field of work (engineering) as a regular worker, I see people working 8 hours but they are not 8 hours productive. Discussing this with some friends we concluded that usually an average developer can focus for around 5 to 6 hours, tops. Then, by adding two hours a day, he won't be 7~8-hours-productive.
My bet (and that's a my own point of view) is that an average developer will keep being 5~6 hours productive. That's because the development process leads to mental exhaustion. After some time people will be much more distracted, leading to mistakes, etc.
Of course there are some folks that will argue that they can do 10~12h work per day. While this is true, usually they don't do it for long without being burned out. A very few exceptions can do that without getting stressed.
So, If I'm a business man and I want my employees to have more free time without affecting my business, I would reduce the hours per day rather then do 10 hours x 4 days a week.
* btw, that's about software engineering only. I don't think the mechanics of other business would work that way.
It really depends on the profession I think. Sometimes you're forced to work really long hours just based on your business.
For example a dentist might choose to work 3-4 days a week, but be open to seeing patients from 9am to 8pm to compensate for people unable to go during normal business hours due to their own work schedules.
Then again I think that business is a lot different than software development. Technically we could sit there and work on 1 thing for 12 hours, where as a dentist is hopping between patients and has a bunch of small breaks through out the day in between patients. It might not be "goof off time" breaks, but it's something that breaks up the day.
Unfortunately most management wont understand that developers can only be productive for 5-6 hours. They often spend most of their time in meetings and will sometimes have 10-12 hour days doing this. They therefore think everyone should work 10+ hours and dont understand that most people that write code can't work these sorts of hours and be productive for it all
Theoretically, the quality of work per hour goes up. More than half of the observed workday in my experience is taken up with chitchat and other bullshit.
