If someone believes that Friday the 13th is unlucky, because they have been told so, and they have a bad accident on Friday the 13th, they are likely to think "Well, that proves Friday the 13th is unlucky".
If that accident occurs on Monday the 9th, or Tuesday the 24th, they will take no special notice of the date. Why would they?
This is how superstitions, once they are started, get reinforced:
|