Why one score, not two
Churn scoring and expansion scoring get built by different teams, at different times, on different data. Customer success owns one, sales owns the other, and the two disagree about the same account often enough that people stop trusting either.
They disagree because they are reading the same inputs and drawing opposite conclusions from the middle of the range. Heavy usage plus rising support tickets is either a customer in trouble or a customer outgrowing their plan. Nothing in a one-directional model can tell you which.
One score, read at both ends, forces the argument into the open. An account cannot be a red churn risk and a green expansion candidate at the same time, and when the model says it is, that is a definition problem you want surfaced rather than averaged away.