The doubling question

Ask of any marketing line: if I doubled this tomorrow, what happens? Then ask the harder half: how would you know it was the doubling rather than something else?

The answers sort into three groups very quickly.

Some activities have a known response curve, a stated saturation point and a way to detect the difference. Those are investments and the conversation is about how much.

Some produce a confident answer with no way to detect it. That is a belief, and it may well be true, but it should be labelled as one and given a holdout rather than a budget increase.

And some produce a long pause. That is the useful outcome. A line nobody can describe the response of is a line nobody is managing, and it is usually one of the larger ones, because size buys a line immunity from questions.

Ask the inverse too, and it is more revealing: if I halved this tomorrow, what breaks and when would we notice? Operations are far better at defending increases than at describing the consequences of removal.