Do breaks on car squeak before they need to be changed or before they can be damaged down to the rotar?

Do breaks on a 2005 buick lesabre usually give some type of sound or squeak before they really need to be changed or can a rotar be damaged while driving a vehicle without and warning. I as because I had two conflicting stories from two body shops and the latter told me that Sometimes breaks can be damaged down to the rotar without any sound which I think was untrue as I think he was just ready to make a quick buck.