Yup, I know I go on about long songs but three and a half minutes is the absolute maximum length of a song if you want it to get air time. Three minutes or less is better.

The ONLY exceptions to this are if you're really famous or if you belong to a group that sings old ballads.

Next time you're at a sing and someone is singing a long song, take a look around the audience, you'll see that most of them are looking at the ceiling or the walls and not paying attention to the song. Is that what you want for your songs?