The Danger of Filler Scenes
Gonna come out swinging, but if you’re writing a novel/novella/etc, you shouldn’t have filler scenes. Every scene should be important to the character, the plot, the setting, etc. If you’re writing a scene merely to have something between two other scenes, you’re going to have to discard it in the long run.
However! What you will need are ‘breather’ scenes - scenes that give the reader a break from heavy action and high tension, otherwise you risk overwhelming your reader by too much happening at once. Consider the following:
Scene: Amy gets into a fight with her ex-girlfriend at the bar.
Scene: Amy slowly realizes a stranger is in her house.
Both of these scenes are going to be pretty tense, if in different ways. You probably don’t want to hit your reader in the face with them right after another, especially because we’re given no time to contemplate what happened in the first scene. So you may end up with something like this.
Scene: Amy gets into a fight with her ex-girlfriend at the bar.
Scene: Amy realizes a stranger is in her house.
It’s tempting to treat “Amy arrives home” as a filler scene, but there’s plenty to do with this scene, character-wise. We can get a good look at her internal dialogue and how she’s handling that fight. We can take an external look at how she’s feeling by how she acts - does she storm through rooms, throw her coat at the wall, march right past that broken lock without seeing it? We can get backstory on the fight here, and how Amy feels about it. There’s plenty you can do with this ‘breather’ scene!
We can also use this scene to establish Amy’s normal environment and how her home reflects her personality. And, importantly, we can use this scene to ease into the tension of the next - Amy might not notice that missing knife from her counter, but maybe the basement door is slightly ajar, and her deep fear of horror movies ensures she would always keep it closed.
Now, let’s say you’re writing a screenplay - with a visual medium, you also want to have a break between high-action, high-tension scenes. But again, it’s a mistake to call these visual breaks ‘filler scenes’ - you may not be able to pull into the character’s inner thoughts, but you can still use this scene to convey that inner conflict. Does Amy drive home with her knuckles tight on the steering wheel, her body language tense and her eyes furious?
How can you frame the drive to reflect Amy’s emotional state? What angle should the POV be, what kind of weather or environment is she driving through, how should the shot be lit? Ultimately, turning a screenplay into a finished visual product is a team effort, and you may not have any say on how the scene is shot (a whole slew of jobs exist to take care of that for you). But if you don’t give your filmmakers and actors anything to work with, you won’t get a satisfying scene out of it. Use the power of description - how the character acts, how the environment appears - to make every scene count.
tl;dr If nothing happens/is revealed/reflects on the character/plot/setting in a scene, you’ll probably discard it. If your character spends a few paragraphs reflecting on the state of their backyard in lieu of directly thinking about their grief about their mother’s death, this is not a filler scene, as important character stuff is happening. Don’t mistake slow and quiet with filler!