takes a tricky melody for the verse. It has to be catchy, and longer than the usual verse. Moreover, songwriters have to spice. It up every time they repeat it with a new thing (like a new instrument in the background, or a back vocals line…etc.). Some songwriters may like this structure because they feel it gives a certain freedom with the lyrics. The other two structures don't give. Besides, this structure gives room for musical intros and outros, not to mention the opportunity to add some musical "breaks" (between the verses) without having to worry about making the song too long.