I thought I'd share a near miss that happened to me a few years ago, while rappelling off of Sedona Scenic Cruise, a multipitch climb. This incident is the reason I nearly always use an autoblock. The day started with a beautiful and efficient climb up the Cruise, and the descent was straightforward, until one instant almost changed everything. I was about halfway down an airy 200 foot rap (double strand) when my foot slipped on the rock. Before I was even aware of the slip, my brake hand left the ropes to protect myself from hitting the wall. My hand made it about two feet away from the ropes before my frontal lobe kicked in and brought it back. Fortunately, my aim was true and I grabbed hold of the ropes, only dropping a foot or so. It was a scary moment because it happened so fast, and also because I was already an experienced climber at that point. It was not a beginner mistake, and it happened beneath my conscious awareness. A reflex reaction, like the time I nearly stepped on a rattlesnake and was jumping backwards through the air before I realized what was happening. Or the time I had a very close lightning strike and my friend and I both dropped to the ground before we were aware. I don't recall the specifics of the rock face - maybe there was a bit of rock jutting out towards my face and that's why my reflexes kicked in like that. But either way, it was a scary reminder that our conscious mind is not always in control of our actions. No matter how experienced you are. I know there's a debate about whether to use an autoblock, but I always use one now. I'm careful to avoid the common pitfalls. I have separate autoblocks for single strand and double strand raps, because the ideal length and diameter is different. I've found that getting the correct length and diameter of the cord is key to a reliable autoblock. And I always extend my descender and attach the autoblock to my leg loop, so there's no chance of it hitting the device.