Unless you have a deadline for a fic exchange or something, follow the muse wherever she leads you. Maybe try working on it for a while and seeing if you can finish it before starting to post again? That way, if you lose interest, or you realize it's not going to be as epic as you hoped, you can scrap it again and no one will be the wiser.

I like to "scene block" the entire fic before I start posting it, so I work through the roadblocks ahead of time and never get paralyzingly stuck once I start updating. But I doubt most people take the time to do this. They want immediate feedback, so they start posting when they get an idea, and then maybe get derailed or get stuck later and can't find their way back... you're not alone in abandoning fics, that's for sure.