Here's a nerdy take on efficiency. In many ways, it applies to CrossFit. With power output being the maximum effective rate of positive return, it is important that we do more with less work. This is most often the argument for the kipping pull-up. It may take a lot of effort to do a deadhang pullup, but you're not that efficient if your task is to pull your chin over the bar. A more effective way would be to use other, more powerful muscles cooperatively with your "back and bi's" to move your body from one location to another, doing the same amount of work with less effort. If my objective was to move a pile of dirt from one location to one a few feet away, would it be smarter to fling it to the assigned area or pick it up, walk it over, and gently set it down? The same work being completed (load * distance) but the former would be a much better way to increase efficiency, and in the course of a workout, intensity.