I believe in training a dog as described above, but last year I decided to put up gates after Teddy bolted out the door and chased the UPS truck down our driveway and into the street.
I thought my boys were trained not to bolt. We had not had any problems for months before this happened. My father is the one who opened the door and he is partially to blame because he doesn't give the dogs commands or handle them in that situation correctly.
ETA: If you can trust everyone in your home, including visitors, rely on training. If not, put up gates too.
