I saw at least one post in here from someone else who has heard the Delta flight attendants announce that passengers should use the lavatory in their ticketed area of service. I have heard this announcement multiple times over the years, and I don't fly every week the same way that many people here do.

Then again, I actually stop and listen to all of the announcements, even the routine ones about how to use a seat belt. Perhaps some passengers tune these out because they're too cool to pay attention?