There is an excellent video on the Sideways YouTube channel called “How Pixar Uses Music to Make You Cry”.
In the first part, he discusses the power of using contrasts to elicit an emotion (eg. play sweet happy music in a sad scene). But there is an idea towards the end of the video that I found particularly insightful. First, watch the video:
When he talks about the scene in Big Hero 6, he says “We want to get an established musical theme that directly contrasts with what’s going on in the scene.” Although he mostly focuses on the idea of contrast in this video, that idea of using an established theme is crucial. He even points out a few scenes from earlier in the movie that the theme could have been introduced in an innocuous way.
This is a really important concept to consider when you approach the spotting process for a feature length film. Rather than focus on scoring on a scene-by-scene basis (“Does this scene work? Does it need help with music?” etc.), it is crucial that you take a big-picture view of how earlier scenes affect later ones.
There might be a scene early in the film that you think doesn’t need music. The performances are strong and the emotion and intent of the scene are clear, so it doesn’t require any support from the score. But this video helps remind us that the music is not there just to support each individual moment, but to give meaning and contour to the entire story.
It becomes more than just “we should have music here and it should be XYZ theme”. It also becomes “the music in this one scene needs to be really powerful, so where are places where we can establish the theme?”. This might cause you to score a few scenes earlier in the film that you would have otherwise overlooked, perhaps even in a neutral way so that the score goes mostly unnoticed. But, critically to his point, you’re getting the theme and its associations into the audience’s ears.