I can see your point.
Having only one day off might more than offset the win from less hours per day, though.
Also, if you need to commute for a long time to get to your work, you'll spend a lot of time in the car/bus/train/whatever you use to commute, and for those who do, this may be very counterproductive.
In short, this might work out better for you, but it's certainly not for everyone.
True, I was more thinking from a work from home stance where you don't have a long commute.
Perhaps with a long commute it would be more productive to have 4 x 10 hour days with two long breaks, provided the company has good break options. When my dad went to work in Sillicon Valley for half a year they had access to sporting grounds and a pool for breaks.
It would mean spending the whole day at the office, 1 hour commute, 4 hours work, 1 hour lunch break, 4 hours work, 1 hour dinner break, 2 hours work, 1 hour commute, 14 hours, leave at 7, back at 9. Yet if the company provides hot meals for the second break, early dinner, and 3 days off every week.
Many days I didn't eat till 9, hence grab BK at the lay over in my commute and crunching on an empty stomach is even more counter productive.
Working with set goals works better than with time, but in software everything always takes longer so you either work a set hours or crunch all the time :/ If the days are already long, less options to crunch too much.
Simply, more flexibility is needed, everyone has different needs and wants.