If a given branch varies considerably in tone or suddenly diverges into a really specific kink, it is because:
1) It is really difficult to try and keep faithful to the flow of a branch when they're not mapped out in advance and chapters are often written weeks, months, even years apart; and
2) I try not to repeat the exact same choices and options, because some folks have complained about the number of futanari chapters or impregnation fetish chapters, so I like to try and throw some variety in there.
Doesn't always work, but I try.