I have an Aunt who has done fast food management quite a bit. She used to work at a Whataburger and refused to be the head manager because it was a 7 day a week job. Employees like to have at least one guaranteed day off a week. I have to assume that Chick-fil-a attracts a better class of manager and employee specifically because they are closed on Sundays, even at the same pay. You really can't understate the value of that.
Bing! That's also the philosophy of Hobby Lobby. We've adopted it too. Working 7 days a week is draining. I would not do it if I wasn't an owner in the company. Your performance starts to suck, your mind is warped, and you just generally are not happy. Personally I don't think you need to make the day off Sunday all the way around, but I'm an atheist, so Sunday has no importance to me. I don't go to Church and I could take Monday off and be just as happy, probably more, because stores and such are less crowded.
A vendor and I got to talking at the counter about Sunday and such the other day, very light, but I mentioned that I do prefer not working 7 days fully open. It cuts my busy season work week down from 95 hours to about 90. He laughed about it only being a 5 hour difference but it really is a big thing. Five whole hours with your family is worth an awful lot when you aren't getting any most of the week. The difference between 45 and 40 hours a week is a laugh. 95 vs 90 is a big swing.