Within the realm of continuity, crosscutting and 180 system allows the audience to expand their knowledge, if the filmmaker allows it, of course.
The 180 system allows for subtle change within the scene, with different shots within the scene in order to further understand the plot, character motivations etc. For example, if there is a scene of dialogue between two characters, there would be a camera shooting a close up of one actor, another camera doing the same for the other actor and a mid-range shot of both of them (there may be more depending on the scene and the film makers choices). If the film maker did not have choices to cut from different angels within the scene it stops the flow of the film, it makes is uninteresting for the audience, the 180 system keeps it interesting on screen. The film maker may choose to keep these cuts between the actors long to build the anticipation, or short to create a sense of anxiety. What the 180 system does is create a depth of understanding and intrigue which ties in with the entirety of the plot.
With crosscutting, the plot alternates shots of story events in one place with shots of another event elsewhere. Such as with 180, cross-cutting creates a greater sense of understanding within the plot. Crosscutting and the 180 system may be combined, as long as the crosscutting follows the 180 system as too not look unprofessional or amateur whilst editing. In most crosscutting shots two or three lines of action are taking place simultaneously. What this does is build suspense and tension, the constant cuts effectively telling two plot points at once, making it exciting for the audience.
Both Crosscutting and the 180 system are both types of editing that are still relevant today, even more so than they were 40 years ago in film.
