Of course, every rule, every announcement and every policy is in place until further notice.
We say it as a form of throat clearing. A way to make the announcement seem more official and specific. We repeat the redundant as a form of gift wrap, a way to be sure that it feels both urgent and impersonal.
“May I have your attention please” is another wasted phrase that is actually self-cancelling on inspection. In this case, it acknowledges that attention is being taken, whether you want to loan it out or not.
This patina of bureaucratic civility exists to let the bureaucrat off the hook. But it also is a signal to the listener that an official is speaking up. We should use it (or not use it) with full knowledge of the signal we’re sending.
It’s the seat belt training video, the do not remove tag on our mattress, the ‘your call is important’ filler on hold and the ritual of singing a not-very-good song to people we care about every single year.
If you look around the built world, you’ll find these tropes and filigrees just about everywhere. As media changes, we strip away the old ones and invent new ones to fill their spot. Use them (or not) as a way of sending a message of awareness and authority.