If the ball is already dead, it is already dead. There is no reason to make any proclamation.
If there are no runners on, there is no reason to announce you are about to bend over.
If there is a runner anywhere and the ball is in a live (but relaxed) state, CALL TIME.
I've told it before, and I'll tell it again (though I am sure the details fade each time). Early in my career and I'm working a double header with a new (but good and experienced) partner. I had plate the first game. During our between game swap out, he asks me "Why do you call time when you go to brush the plate? Everybody knows what is happening." I shrugged and called it a habit.
During the second game, he has plate. With play relaxed (LIVE!) and a runner on third, he comes around to clean plate. As he is sweeping the plate off, R3 comes sliding past him. The defense starts squawking (of course). He settles everybody down and comes to me for a quick meeting. The first thing I said was, "That's why I call time." The second was, "I didn't call time. So, unless you did, I have a live ball and a run scoring." Fun!