I generally dont engage the safety on my gun at all, I just keep it pointed in the correct direction and keep my finger off the trigger.
That said, a couple of weeks ago I found a use for my safety for the first time. I was battling a full size male sheepshead crab trying to control his claws and get him into my NHT bag (barely fit) when he managed to grab onto my loaded gun that was hanging from my float line (wrapped around my wrist) down below my waist. To my distress he got several legs around the gun and had one inside the trigger guard!
I had to let him drop, and after he let go of the gun I dropped it to the bottom so I could re capture him. He was a big 'un and worth the fight as I extracted over 1.5 lbs of clean sweet meat from his carcass.
So there you have it, I have found a good use for a safety; i engage it when struggling with crabs, I'd do the same if dealing with an octopus.
Jeremy