Let's face it: most of us plan our dives thinking nothing could go wrong. Perhaps we would be better served to plan for the caca hitting the fan. I carry 3 light in a cave, on night dives, and at least one on OW dives during the day. When I dive heavy doubles, or my rebreather, I dive a double bladder. Fun dives close to shore, I really don't have a problem with no bladder, but not normally in OW. I've been surprised with many an anchor while diving. Without a BC, they would not have been collected.