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.
“I think hearts are very much like glasses. If they do not break with the first ring, they usually last a considerable time.”
“The five steps in teaching an employee new skills are preparation, explanation, showing, observation and supervision.”