France had a 39-hour week, variously interpreted as eight-hour days and leave an hour early on Fridays, or 5 equal days of 7 hours 48 minutes, or (often) as "a minute here or there doesn't really matter, just work".
Almost 20 years ago France moved to 35 hours, with no change in monthly pay, recommending (I think it was a recommendation) that work days continue to be 8 hours but that employees be given whole days in proportion. The legislator (quite correctly IMHO) estimated that 48 minutes less per day would not have a real effect, being lost in overtime and "we don't count minutes". Since no general standard was enforced, this was variously applied as "one half day off every week", "one day off every two weeks", "two days off per month", and "we have an exemption so you continue working 39 hours but we'll have to pay you more". Also as "You will now work 35 hours for the same pay, this is marvelous country-wide social advancement that you should be very happy about, we're really sorry about the 32-hour week you had before but it's the law, you know", which caused some sour glares from postal workers.
20 years later, I don't know the exact results of the studies made (there have been lots), but it is sure that nobody is going back. Kids were already on 4 1/2 day school schedules, and parents are happy about spending more time with their kids (or paying less babysitting), other parents get time off when the kids are at school, and more simply people have gotten used to being able to take a day off now and then, to go to the doctor's or any other professional or shop not open on Saturdays, or just to do housework or work on a hobby.