Every time I have been hurt it happened in relatively small surf. I broke my nose on a knee to thigh high day, got my teeth knocked out and a waist high plus day, gashed my arm on a chest high day, chipped my skull on a shoulder high day. Now that I'm older (mid 40's) I don't venture out when it is absolutely macking which to me is head to overhead top to bottom barrels. Mushy head + I will still go out but am very conservative.
My buddy got knocked out cold on a small day (knee to thigh high) while nose riding. Nobody actually saw it happen - he was up - and when we looked back he was in the water not moving. Somebody grabbed him right away and he came too almost immediately while coughing up water. I'm not sure if he would have came too if he wasn't pick out of the water so fast. It looked like his rail hit him on the temple cause the rail was shattered. Needless to say he had a lump to match. Anything can happen and with out help it could end up bad. I respect anyone who dosent want to surf alone now.