If your property is posted, no trespassing, anyone on the property without your permission, is a trespasser. My dog would not go for the throat, but he wouldn’t let anyone he does not know come on the property. Once the a person steps off the property, my dog stops the chase.
It depends on how professional and how serious the would-be robber is. Dogs certainly have a place in home security, but real pros often shoot, stab or poison dogs. They’ve “cased” the property so they already know about the dog and come prepared to deal with the dog. You won’t be home when they come. But for the average punk with no gun and no real plan, a serious dog is a real good start at prevention. It sounds like yours is a good watch dog. Training him/her to attack on command or at intrusion into any building on the property would be better. If you do that, be sure you post proper warning.