An OOA diver situation is not always going to be because some one was not watching their air, as I think has been assumed here several times. It can be, but it can also be a real emergency: I was diving near another group a couple years back where, on accent from a 100 ft certification dive one of the divers had their high pressure hose dramatically fail. THAT was a real OOA situation where sharing air at (only) 15-20 ft was critical!!!
I think you mean low pressure hose?