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 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.