The Sig and revolvers have built in safeties via a long DA trigger pull. I'm talking about using a gun the way it was designed. The OP was asking about not using safeties even if the gun has one. Rifles, shotguns, SA semi-autos have manual safeties and they are meant to be used. We all suffer occaisional lapses of good judgement and I like the redundancy of mechanical safeties.
I've never seen a mechanical safety fail. I've seen a lot of people do dumb things in handling a firearm. If a person is afraid they will forget the safety is on in a critical moment they need more training.