They say there is a chance to get into a Binged section (that is supposed to highlight the completed stories). Plus, if you start new series, people who read that will see your other works on the side bar when they read. If they like what you have now, they might check out the other stories & if they still hold a place on popular after completion, Staff Pick may be a possibility?
Heh, I am hoping for some traffic after completion, because I complete fast.