A song is like a saddle: you ride it for a while, and if it's the right kind of song you can sing it for the rest of your life.
When I write stuff and I help cast it, I turn away good people all the time. I may turn them down because this one's too tall and that one doesn't have a high enough voice or this one looks to old to match up with that one - there's a billion reasons not to hire somebody.