It really depends on two things:
1. The attitude of the franchise owner; and
2. How frequent of a customer you become.
When I lived in my apartment, I would frequent one particular Subway on average of once/week, often for Sunday "brunch." The service was great, they didn't mince on the veggies, they kept the place very clean. About six months before I moved, a Subway opened less than a block away. I went in that place a couple of times, and the attitude/service was atrocious. So I started going back to the other place, even though it was a two mile drive.
Now, I have a Subway four blocks from me, but I've never been there. I have better food options, including a Mexican place in the same plaza. But I do have three BOGO coupons from my Entertainment book, so maybe I'll try them this weekend.