With increasing rents on retail space, how sustainable is that policy? Could the difference between customer flow 7 days a week and 6 days a week make or break a location?
The majority of Chick-fil-A's are not renting their space. Most Chick-fil-A locations are built new on free-standing property physically owned outright by corporate headquarters and franchised to Owner-Operators with a revenue sharing model.
(BTW, it also says they gross an average of $4.8 million per year per location, in 2016 at least. That's the highest sales of any Fast Food franchise in the US, vs the next in line, Whataburger, at only $2.7M per location per year. So being closed on Sunday doesn't seem like a big issue for them.)
The Chick-Fil-A locations I remember from two decades ago or more were in shopping malls where there was definitely lots of dead time during the week, and therefore one would think they would need to be open on Sundays to make up for it. So, I’m surprised by the high-volume concept you link to (though WFLA’s anti-GDPR policy prevents me from viewing it), though I have of course heard that shopping malls are less prominent a feature of the American retail landscape these days.
I’ve personally never seen one in a mall but I’m also not in the South.
The ones where I am are double lane drive through where the lines snake around and there are people roving the lanes to take drive through orders before they even reach the window.
