Can you increase the fan reach to 100% when fans connect to your site using facebook connect or a custom made app?

I noticed that when you use a custom app on a site or page a pop up box shows up asking you for persmission by the app to post on your wall as yourself.  

So if I give persimission to an app that requires this permission or use fb connect to log in a site,  Is it a safe assumption that the site admin can post to the wall of 100% of the fans who at least gave permission to the app to do this?

@andrea-vahl   @briancarter

Sorry for the delay in getting back to you on this @carlosdixon  The App permissions are different from the Facebook page and won’t count towards the reach stats of that page.  

If you started posting on the Timeline of all the people who have given you permission for your App every time you had a message for them, you would probably loose a lot of app users quickly.  Hope I understood exactly what you were asking with this question!  If not, let me know