Think of a favorite scene from a favorite movie. Somewhere in the hundreds of individual frames on the film stock from that scene will be a single "still" frame that captures the essence of the scene. That is, a frame that when printed as single image distills the essence of what has just happened and is about to happen in the scene.
With Wall's work the lighting, staging, actors, directing and final presentation all are used as with a motion picture. But Wall doesn't need a few thousand feet of film stock. His movie is contained in a single frame.
I think the subject of a particular image seems to provide a single "still" frame from which the viewer can work both backwards chronologically from the image or project into the future about what comes next.
I don't recall if I have seen any of his work in person. From what I can find on the web, I would say that some of his images work much better then others .