My wife recently got re-certified in first aid and CPR and was able to use those skills the other day on the street.
Walking home, I realized being certified isn't necessarily about providing the aid. I didn't stop the bleeding, though it subsided on its own. I didn't try to examine her. This was in part because she refused my help initially but also because I knew the ambulance would be along soon. Mostly it was about providing comfort to someone in a difficult situation, helping them feel ok, and letting them know they weren't alone. The certification gave me the confidence to do that: to kneel on the sidewalk, holding an old woman's hand, and to help make those scary few minutes hopefully just a little bit better.