What Luis_H and Blackwood said.
I know of several real life OOA "saves" using buddy breathing in the mid-70's and early -80's. It was stressful, but no panic.
I've personally never gone OOA, nor have any of my buddies, even when we were all using J-valves. So I've never had to use buddy breathing other than in practice situations.
Prior to widespread use of the octopus, we were trained to buddy breath. I believe the octopus is certainly a better solution for sharing air, but like many I feel that buddy breathing should still be part of the basic OW curriculum.
Safe Diving!