Rules on a poster change nothing. The rule people actually follow is whatever the leader did last Friday.

The rule a group actually follows is the most recent precedent rather than the printed statement. If something got let go last Friday, that is now the policy whatever the poster says, and everybody noticed except possibly you. Rules live in actions, and the written version is only a record of an intention.

Think about the last exception you allowed and whether you are happy for it to be the standard. If not, say so out loud and go back to the original. What you do this week is what the rule becomes.