I stop them only when necessary. It's far better to just have them grazing, head down and lessen their chance of jumping the string than it is to have them posing and staring at you!

But yes, I do stop many deer as I usually catch them in a browsing mode where they are walking along not pausing much and because I also frequently have small shooting lanes. Having said, that it's usually just a "meee" type of a noise and it has stopped all but 1 deer, who at the time, was chasing a doe- hard! They'll never stop