I think a constant flow of fresh content is the biggest problem that larger sponsors tend not to give enough of - If, say for example, you have 10k of referring webmasters, those doing tgps will grab all the new content recently added - Which then means tgp owners (we run a couple) get much the same content from a few different submitters - This cuts down the chances of the submitters making cash.
(You must see this yourself time and again on your tgps).
