I’ve worked both 3 and 4 day weeks (at 8 hours a day), and it was always really great, but it made me feel I was missing so many things in the workplace, I’m now not particularly bothered by working 5 days.

But if you want to do a lot of things beside work, 3 days is best.

It’s also a bit dependent on life situation. When I left university I was perfectly good with 3/5ths salary, but now with a family to support that would be hard.