What is your opinion on grunt calling during the rut.

I usually only grunt call when I spot a buck during the rut. And the results are usually 50/50 depending on what type of mood he is in or whether or not he's king of the area.

My question:

On Saturday I was doing some short grunts about a half our before dark ( or what we call deer : 30)

Have you had any luck in bringing a buck in (that you can't see) by randomly grunting?