I’m Dutch too, and I used to work 8h/day 4 days a week. And my productivity became even better than when I worked 5 days a week. I could kill it those 4 days, and be rested enough the next week so I could kill it again. It worked wonders.

I like the rhetoric, because it means that my employer got something out of it too. But I don’t think it implies that was the only reason it should be given. I obviously enjoyed the time off for my own reasons.