I teach that in all OW classes
markfm:Buddy breathing and unconscious diver? In a basic OW class? What org did you train with? (No, it's not the norm overall, today. Out of air drill, using your buddy's safe second is the norm, with buddy breathing [sharing a single regulator between two people] at most an "option", pretty rarely taught at the intro level; it's much simpler to stress not to dive with a buddy that doesn't have a working safe second, and that checking that is part of your surface prep. Surfacing an unconscious diver is a Rescue scenario.)