Training never ends. It's great when the brain just kicks in without thinking, like what has been practiced and "thought about" repeatedly.
We practice drills at home, at work, and in the vehicles. You never know what's going to happen, but we believe that we are ready to go for our protection without having that 1-2 second delay while you try to comprehend something that's occurring around you.
When seconds count, I don't want to be one of the sheep that has to analyze everything before realizing that a threat is there, and I may not be able to defend myself or take defensive action in time.
My wife and I play a game in the car, where we'll unexpectedly quiz each other about what vehicle is in front of the one in front of us, two cars back, or what the billboard just said that we passed. It's about training the brain to always be scanning, listening, and being aware of things out of the ordinary. Then when something happens, you can react instinctively without hesitation.