I get paid overtime rates for any work on Saturday (150%) or Sunday (200%), and for any work in excess of 37 hours in a week.
And it's cumulative; If I work more than 7h38 on Saturday, I get double time (50% of standard time for Saturday, plus 50% for more than 7h38, plus my base wage).
I worked on New Years this year, until 2am on Saturday 1st January, and was paid 350% of my base rate for the first 5h38, and 400% for the last two hours (it's a gazetted Public Holiday from 6pm to midnight on 24th and 31st of December in Queensland).
Given the massive productivity gains due to automation since the 40 hour week was introduced in 1947, (and subsequently the 38 hour week in 1983), it would make sense to me to make the working week 32 hours, typically including three full days off, with a maximum 8 hour workday.
There's nothing particularly fundamental about the traditional seven day work week with a half day off on Sunday - as was the norm for centuries in North Western Europe; Nor about a six day week with Sunday off, or a five day week with Saturday and Sunday off.
Working four days in seven, with suitable compensation for voluntary overtime beyond that, seems completely reasonable to me. We work to live, not the other way around.
If we made the weekend Friday, Saturday, and Sunday, that would make most major religions happy, and align the working week between Europe and the Middle East; Better still, we could make Saturday Sunday and Monday the weekend, which would annoy the Muslims, and provide a huge economic stimulus by forcing Garfield merchandise to be re-issued