Taz has snuck out several times, but he never goes very far from the door. If something spooks him he runs for the safety of the house. He does voyage to the garage a lot. He sneaks out the door when I'm out there changing laundry loads.
Paizly has never set foot outside this house since I got her last July. Luckily neither of my kitties are door darters, but we are very careful about door being open (or broken screen doors).