If you want to get your message out, you have to do the work.
Don't count on people hearing your message until you put it directly in front of them.
Sometimes you have part-time staff who aren't always around. Or staff on different shifts.
Use technology to make sure all staff members hear the same message no matter what time they work. Or, move around meeting times. If you want to figure it out, you will figure it out.
Don't worry about annoying staff by getting your message out so often. Worry more about making sure you are clear.
Write out what you expect, why you do what you do, and what employees can expect.
If you want to get your message out, you will have to say it over and over. When you feel like you are saying it too much, people are just now beginning to pay attention. You have to get the message to staff on different shifts and in different ways.