i got rejected once for a comic but got in twice later. i got a rejection neomail, an acceptance neomail and a your-comic-is-being-held-for-future-consideration (aka wait-a-few-weeks-but-don't-submit-again) neomail.
i believe the comics decider is one person back then and she gets 300 comics a week.

so if you don't get published, don't send in the same story every week becuase if you don't get in the first time and the tnt staff didn't want to keep it for future publication - they have no lack of stories to chose from, then try again with a different story. but maybe ask the regulars who do get into the nt a lot? there's a major nt guild and an online nt forum somewhere else too...

and i know for the pet/petpet spotlights, you don't get a reject neomail either. if you do win, it takes like 2 months for tnt to put it up anyway.