I agree with you that getting paid the same hourly rate, working less and still maintaining job stability is a win.

It just didn't initially sit right with me when I heard Look at me I'm winning! I used to do five days of work and get paid for five, now I do five days of work and get paid for four.

They were doing four days of work and getting paid for five, now they do four and get paid to do four :)

I also went from 8 hour day to 6 hour day with a cut in pay and no loss in productivity and I feel it was a win. I've enough money either way and a lot more time.

Well, it's obviously a baked in assumption that the employer wants to provide as little remuneration for value as possible without alienating the employee. In theory our compensation is based on some combination of the value we deliver and our negotiating strength. If we deliver the same value in 80% time and take home 80% of the compensation, we've fully left negotiating strength on the table.

Your assumption is that they were doing 5 days worth of work in 5 days, and now they're doing 5 days worth of work in 4. But they're just more productive, they're not busier. So it sounds like before they were doing 4 days worth of work in 5.

I think it really depends on what the work entails. When I’ve worked on some particularly complex problems it’s often the case that I get “zero” days’ work done for four days, then “dozens” of days’ work done in one. My assumption is that a person has a fairly fixed productivity capacity over a given stretch of time, that we as a society tend to organize that as a week of seven days, and that it’s highly likely most people (again depending on the work and the person) reach that capacity in less than five days.