In engineering and in any high-reliability operations, it is standard to eliminate any single point failure that could cause something bad to happen. In other words, it must take more than something going wrong to have a bad outcome, It must take a chain of multiple things.
Of course Libby and I practice that when cruising. I've written before about the nasty box canyon scenario. More mundane and everyday, we keep far enough away from other vessels to prevent a collision if something goes wrong. You do the same when you drive your car down the street. (You do don't you?)
But it is harder to follow that rule in everyday things we do without thinking. Case in point. I realized that Libby and I have both fallen into the habit of holding the dinghy painter in one hand as we climb down from Tarwathie into the dinghy. If we should drop the painter, the dingy will be gone downwind and we will be ip the creek without a dinghy.
I had to force both of us to modify our habits.