title: iad banner - one instance per app or one instance per page
body: <p>Is it more appropriate to have one shared instance of and iAd for my app or can I create a new instance on each page of a navigation app?  It seems Apple's sample code has only one ad that is used one each page.  From my perspective more ads means more money.  Is there an issue doing it in this manner or am I looking at this incorrectly?</p>