Random snap caps are a great exercise. I don't even need someone else to put one in. I try not to look at exactly where I'm dropping it in and I do forget where it's at. I'm amazed that even though I'm working a drill and KNOW it's coming, I can feel my brain come to a screeching halt and try and think through the steps to clear quickly and smooth. Probably 50 magazines of this exercise so far and sloooooooowly starting to become somewhat natural.
The ah-ha moment for me was the event in Michigan with Sean Ruis. I was really surprised at how quick he got his hand on the LOE's gun but REALLY impressed with how fast she cleared and continued firing. She did not miss a beat (by my untrained eye) By the way, it seems really hard to find the full footage.