Own a number, not a calendar of activity.

Most marketing is accountable to activity: pieces shipped, posts scheduled, campaigns launched. Activity always looks fine, because activity is the one thing a busy team can guarantee. The question a calendar can never answer is whether any of it changed what a buyer did. The Growth discipline is one number, three tests: a sceptic would accept it as mattering, your work can plausibly move it, and you can read it weekly without asking anyone. The number is read on a fixed day against an agreed pace, and a miss changes next week's plan on the record. A number without a sensor does not exist: if reading it requires someone to remember and paste, the reading stops the first busy week, silently. The number is what the other six disciplines answer to. Our own machine once owned a number that measured the wrong thing: being mentioned by AI engines, counted as being chosen. The fix was a harder definition of the number itself. Part of Growth Engineering; test yourself with Stack Score.