Here's an interesting story about a woman who has been eating at the same restaurant for the past 20 years. She goes once a week and orders the same thing—something she made up that's not even on the menu.
Now that's customer loyalty.
The closest that I've come to that is eating at ZivaZ about three or four times a month. It's walking distance to my house, and the food and service is light years beyond other fast-casual restaurants. I have a favorite—the eggplant Milanesa—but have recently tried other items on the menu, too.
Do you have a restaurant that you regularly patronize and if so, for how long and how often, and what do you order?