Let's say music is needed for only 43 seconds of film. You have to score it so it is an entity, so it won't bother anyone when it ends so quickly. Or if a song runs 2 minutes and 45 seconds, but the titles run a minute longer, you have to arrange that song so it doesn't get repetitious.
Marvin HamlischNormally I can balance two or three things. The problem is when you're out of work and don't have anything to balance. I think people assume you're always busy. You go through dry spells.
Marvin Hamlisch