How, and when, did we all come to the agreement that a song should be roughly 5 minutes long?
Obviously there are plenty of exceptions for this, but typically songs (especially those that air on the radio) are 3–7 minutes long. When did this become the standard? Is there some fundamental reason why we prefer songs to be this length? Why does it seem odd for a song to be 30 seconds long? Why do we often dislike songs that are 10+ minutes?