Not necessarily. I have a single save with neutral chick MC and I have seen every scene and fucked every girl I wanted to. As much as Prickcake wants to, he still hasn't found a way to beat a simple editing mod tool.So just a regular DIK playthrough?
I play the game as it were "Schrodinger's DIK". Until several variables are defined all routes and paths are possible at the same time.
EDIT: Except Zoe, Jill, Jade or Bella's routes. I wouldn't touch either of them with a hazmat suit on and a 10-foot pole.