That means you can't afford any scenes that don't pull their weight. You should know – specifically – what purpose each scene is playing in the story. Today I want to look at some valid purposes for a scene. Every scene in a screenplay should do at least one of the following things:
Advance Plot – Any scene where the story moves forward is a plot scene. As you might expect, this is the most common purpose for scenes in movies. But a scene is only considered to be advancing the plot if the situation in the story has actually changed from the beginning of the scene to the end of the scene. Don't confuse activity with advancement. Scenes that advance subplots are a subset of this category.
Reveal/Advance Character – This includes character introduction scenes, scenes where we learn something new about a key character, and any scene where the character changes. The way we reveal character is through behavior (dialog can count as behavior as long as the character is trying to accomplish something with what they say). Often character scenes also have another purpose. For example, a scene may both introduce a character and advance the plot. You should avoid too many pure character scenes, though a handful are acceptable.
Preparation – Often we need scenes to prepare for the big plot advancement scenes. Usually these are scenes where the characters are preparing themselves for the upcoming event. Preparation scenes allow us to plant things that will pay off in later scenes and to get out critical exposition. In fact, there's a subset of preparation called the expository scene – the scenes where James Bond is getting briefed on his mission, or where Indiana Jones describes what is needed to locate the Ark of the Covenant. (Expository scenes are usually boring, so limit yourself to one if at all possible.) Preparation scenes also give us a chance to show how the character feels about the upcoming event – and are thus often also character scenes.
Aftermath – Often we want to have a scene of aftermath showing the impact of a plot scene. The impact is frequently an emotional one on the character, so these are usually also character scenes, though sometimes the aftermath is more expositional, showing how the situation has changed as a result of the last plot action. It is not uncommon for scenes of aftermath to morph into scenes of preparation. And any denouement scenes at the end of the film would be considered aftermath scenes, showing how the story has affected the character and the world.
Pay Off the Genre – If you are doing a comedy, you better have several really funny scenes in your script. If you're doing a horror film, you better have some really scary scenes. Usually and ideally these scenes also advance plot. But every once in a while you need to include a standalone scene just to deliver on the expectations of the genre. A good example would be the fake orgasm scene in When Harry Met Sally... (written by Nora Ephron). It doesn't really have anything to do with the story, but it's the most hilarious scene in the movie. This is the key – if you're doing a purely genre payoff scene, it better be great!
There are two times I use this list in my writing process. First, when I have what I believe is my finished outline, I'll go through and identify the purpose of each scene - specifically to that story. So the purpose of a scene might be: "Character advancement – Kelsey decides to trust Dominic."
The second time is when I'm preparing to do my second draft. I'll go through every scene in the first draft and reevaluate what its purpose is – and whether it is fulfilling that purpose effectively. It's important to be honest with yourself here. The purpose of the scene should be apparent. If you're reaching to come up with the reason the scene needs to be in the script, it probably doesn't have a real purpose.
And if it doesn't have a purpose, it should be cut.