Ehh, maybe it started of as a religious thing, perhaps why Sunday was chosen specifically; but the idea of forcing everyone to have a day off is wonderful.

In the us, there's no federal law limiting the number of days people have to work. Some states have a 1 every 7 days rule. But that's not specific enough, for shift schedule work, they can set your off day to be Sunday this week, and Friday next week, and only schedule you a few hours a day so you get to work almost 2 weeks in a row with out overtime pay.

IMO, it should be (regardless of number of hours worked) on day 6 your pay is 1.5x, and day 7 is required off. At day 8 it's 2x pay, +2 days of paid vacation time (worth 8 hours or your typical shift length (which ever is larger)). It all doubles each day with out a day off. With a signed agreement between you, HR, your boss, whomever is "in charge"/owns the company and the labor board with specific documentation explaining why you have to work so many days in a row and why the job can't wait a day or someone else can't fill in. Failure to do this step results in x5 back pay for everyday worked after 6. Doubling everyday after 8.