I feel like that's generally the best measure of success.  If it lasts two pages and everyone had a good time or if it lasts four threads.  There's success and then there's like legendary success.

If everyone had a good time that's a success.  If it's two years later and youre still talking about the RP with its participants that's legendary.  It's a nice thing to hope for but it wouldn't be legendary if it were common.