At a previous position. We worked 15 mins extra a day from September to end of June. This allowed us to take 7 Fridays off in the summer and reduce the hours for the other 4 days of the week by 1/2 hour.
I do feel that positivity went up and our work did not suffer from this, overall, the culture was great during the summer months.
Right now, at my current position, I have one employee working a 4-day work week but, they work 4 10-hour days to have a 4-day work week.