Surely that's explained by factors like the market segment they're in? Just by math alone you'd expect them to have 15% less sales from having less hours open. Maybe 20% if you factor in that Sundays has more traffic than other days of the week. But it's not as if them being closed on Sundays can plausibly boost productivity. They already presumably have people working in shifts, so it's not like each worker is working less hours.
Why is everyone so obtusely harping on the Sundays point?
Sunday is one of the days of the week with the highest sales. Chick-fil-A manages to make significantly more revenue in spite of their closure on Sundays. And what could be driving that? That was my point - that good corporate culture (which again does not mean 1-day-off) throughout the company has resulted in one billionaire enterprise out matching the rest.
I literally just mentioned the Sunday day off as a footnote, yet everyone seems to have harped in on that without the context of my parent comment.