I have the main storyline's ending in my head, and I have some major happenings along the way. But as far as a lot of girl-interacting scenes go, I make them up as I go along.
I know the story with Christine will have A, B, C, D, and E along the way. But I can insert scenes between B and C, and between C and D, to get more interactions with her along the way.
Also, the polls are just extra scenes with two of the girls. They make up maybe 15-20% of the update, the rest is all me.
But does it all make sense? Well, you be the judge :)