You had to write something that everybody could sing. So you wrote something that was catchy, that was short. You wrote the stuff that would stick into somebody's head and they'd be able to sing it right away. Imagine, there was this country from the Atlantic to the Pacific where people were singing all the time. They were singing in buses, they were singing in their houses, they were singing in the park, everybody was singing.
Radio comes in.
You're writing songs specifically for Bing Crosby. This one song was written to be recorded once by this one person, not by a lot of different people. You can do it in pieces and the song never gets sung. What we call a song is pieced together in the recording studio. You write a song and it's really never sung.