Editing is a necessary requirement for any filmmaker and this article explains some of the reasons for post production.
What is the answer to the question, "What makes a film or television show worth watching?"
The answer is both a simple answer and a very complex one at the same time. The answer to the question is - You - the viewer. What do you want to watch the film for, what are your values and needs, what is your emotional state at the time, are you looking for distraction or escape, are you watching for the educational value, all these question boil down to the one answer, what makes a film worth watching by you, the answer is you. But to get the movie to the point where the viewer will want to see if the production is worth watching, it must be edited for enhancement
Now what enhances the film to be viewed and memorable are its elements, the story, the performances, the lighting, the choice and quality of film or digital medium, the sound quality, the choice of music, especial the underneath (background) mood music, color corrections, and the cuts.
Editing or post production is crucial to smoothly including all the elements of a good movie. Some of those elements included are as follows.
Cutting or the "dicing and slicing" of a movie. A good movie will change cuts every 10 to 12 seconds and that is why editing is very important. The cut of a frame can make or break a movie. Is there a Dutch pan (Tilted shot)? Is the movie an action or horror movie, does its use of jump cuts effectively drive the show or are they in the way or superfluous, does the cut list work or is more footage needed. Does the scene call for a clean shot, did the director want a dirty shot (this means that they wanted a grainy look, not a porn shot), or are the frames out of focus and muddy to form a cacophony number of cuts to indicate a POINT OF VIEW of a fight scene, such as in the movie, Rocky, when he almost gets knocked out? Is the footage in focus, purposely out of focus, or did someone just have a bad day of shooting and shot almost nothing that is usable and if it is badly shot what can be done in post to rescue or save as much as can be saved.
Color: What is shot on one camera may not be color aligned or balanced properly to match another camera or even previously shot footage shot on a previous day, therefore an editor is need to give it a professional edge. Color corrections might be as easy as lightening a frame or two, or it can be a very time consuming and expensive color edit, requiring everything from color matching, lightening, balancing the background, stepping up the image and re-digitizing after the bump.
Sound and Music: Sound is very important, it must be crisp, sound effects, if used to draw attention to a turning point in a movie, such as a backfire from a car or a crashing sound of metal on metal when a sequence calls for a car crash, must only draw a temporary focus to them, but then must quickly return the story to its driving element, usually the characters moving the story. Sound is more important overall as the comfortable background noise running under the scene. Audiences hate silence. Music editing, while most people are aware of the Title song, if it is sung and or played by a popular musician, but the background music, that is played underneath to draw a certain emotion into the scene, is equally, if not more so, important to the film and it must be edited in such a way where it is seamless and does not interfere with the audiences enjoyment of the movie.
Post production is very important. It is the final polish of a process that may have taken a long time to put together. It is the magic and seamlessness of sound and image bits, shot and running simultaneously, that form the smooth flowing visual story presented to an audience.
It can also be the most frustrating part of making a movie and many decisions a day a chosen. This can lead to many differences between the deciding parties, such as the editor, the Director, and the Producer. As for the producer, the film may need some more camera work done or it may need ADR time scheduled at a sound stage, and wild sound recorded, and that means going into contingency funds. The director may be looking for a specific look and finds that the overall look just never gelled and has to settle for "the best we could get at the time." Sometimes that director does not see the movie they had envisioned at the start, sometimes for the better, sometimes for the worse, and asks the editor to take over the final editing only to see that the editor did not see the same movie that the director finished in production. These are creative difference and this is the minefield of post production. People's reputation and careers are at stake. Equipment is constantly changing. But it is the most necessary part of making a professional movie commercially viable.