If I might generalize on what you said, "focus 100% on the movement that gets you to the trigger," is almost the same thing as saying increase your awareness of what your body is doing during the shot. Awareness is an immediate physical focus, which includes being aware of the movement that gets you to trigger, as opposed to a cognitive focus, which is an abstract thought about what you're doing, or what the result might be. Physical focus cannot be expressed in words, whereas cognitive thoughts are usually in words, emotions, or visions of something imagined.
This is why Joel asks people what they were thinking about during the shot. ANY (cognitive) thinking is the wrong answer, because all focus should be on increasing awareness of the mechanics of the shot, which is non-verbal. The problem is, as human beings, all of our recent accomplishments, from the invention of agriculture 15,000 years ago to landing on the moon have been based on our success at cognitive thinking. Cognitive thinking is so ingrained in us that it can be really hard to answer Joel's question, because we have a hard time separating our cognitive thoughts from reality. But thinking ABOUT something is different from doing it and experiencing it. Thinking about things in the abstract has enabled humans to imagine better ways of doing things, but it doesn't help us to actually do them; for that we need awareness.
The point in trying to generalize on your statement is that you don't need to focus solely on the movement that gets you to the trigger, although that is a lot better than THINKING about the movement that gets you to the trigger. Any way that you can expand your awareness of what your body is doing during the shot, whether it is a movement of your head, the position of your elbow, or the physical anxiety you feel as you build tension, will improve your shooting, as long as it is a physical awareness and not an abstract cognitive thought.