As humans, we don't like to change much. We relish our routines. Since we're prone to doing the same thing again and again, we self-justify why we make the choices we do.
If I eat lunch at the same place every Tuesday, I will quickly understand the range of deviation in my experience at The Tuesday Place. The more trips, the more I can explain away a bad lunch, because I have so many more positive lunches to balance against it.
In other words, it only takes two or three consistent experiences to lock in, for better or worse, where you will live in that customer's mind.