There are lots of possibilities for the End Titles roller or sequence. The fashion for inappropriate songs crashing in as soon as the film’s finished, or sometimes before, is still with us occasionally. The rest of the roller would then either be filled with other songs with little attachment to the film or a montage of score cues cut together by the music editor. Some of these are better than others.
Other directors are much more involved in what happens, particularly in how the final moments of the film move into the titles. On Children of Men, Alfonso Cuaron crafted a beautiful transition with sound design and music in the credit sequence. The sound of children’s voices, eerily absent in the rest of the film, blend into the start of John Lennon’s “Bring on the Lucie”, an entirely consistent choice with the rest of the music in the film. He also found room for Jarvis Cocker’s iconoclastic “Running the World” which was a hidden gem for those who stayed in the cinema long enough!