This is Brian -- I wrote the article. We are closed on Sunday but its not dogmatic in nature. We want to make sure that everyone at Chick-fil-A has a great work/life balance. Occasionally we need to do some work on a Sunday but we try to architect and engineer in a manner that supports business-hours-friendly deployments, or scheduled deployments over night to protect that. This is truly a first-class design consideration. In my 14+ years at Chick-fil-A, I have only worked a handful of Sundays for any reason. Its a tribute to leadership at all levels and a great company culture that values people (and their need for times to rest).