A goal-driven ruleset does not have to answer the same question every time. Override its goals per run, from the runner or from an API call, and one set of rules can answer eligibility today and pricing tomorrow without being edited.
Every mature ruleset accumulates logic that no longer does anything. Here is how to find it in an afternoon, using the fire rates on the Analytics page and the Verify tab, and how to tell dead rules apart from rules that are merely waiting.