When I walked Indy in a prong, yes, I had a libertys attachment or something similar attached to a collar or martingale because Indy can walk right out of leashes. She doesn't slip her collar, but she unbuckles the leash clip some how. I have no idea how.
She wears a Neck Tech now, and it's a limited slip collar, and so far she hasn't walked out of it, so I don't have a backup on her. However, she's now microchipped, and you couldn't pry her away from me if you tried, so I worry a lot less about it than I used to.