How often should u have to change a serpentine belt on 2004 Dodge Caravan? on 2004 Dodge Caravan

Serpentine belt replaced 2009, idle pulley and serpentine belt 2010, now 2013 belt replaced again yet loud noise still there!

1 answer
Why is it being replaced? Splitting, coming off, breaking or a shop keeps telling you it needs replaced?
I've owned 4 Chrysler mini vans with a 3.3 and replaced the belt when bought and never after that, at least 5years owned on all