That would defeat the point - time with arse in seat does not equal productivity.

I switched to a 4-day work week years ago, and still work 7.5h each day. I found that I'm much more focused during working hours, and spend less time procrastinating - I'm just as productive as I was before.

I would do 10 hours day for Friday off. Working an extra two hours doesn't put a huge strain as you are already at work or in the work mode. During crunch time I would end up working until 21:00 to 22:00 and I felt it was like exercise in that as long as you don't stop it's not as bad.

You also avoid commute overhead if you work from the office.

Working 5 10 hours work days (at least ) already , four would be great.