We found a little dog on the side street and took her home until the owner could come get her later that day. She could easily have wandered a short block to the main road and that might not be good. She had escaped from their yard and they were unaware.
My dog is closely guarded and in a harness when we take her out. She also has an extra strap from the collar, wound in the harness then back through the end of the leash (past the clip part), so that if the leash disconnects or breaks at the clip end, she will still be on the leash. This proved good once when she got spooked by a giant rabbit (person inside at flower shop) and lurched back so hard she slipped her harness and all that was left was the collar and that extra strap.