Rules become dangerous when nobody can explain why they fired. A useful traffic rule has a narrow condition, an explicit risk adjustment, a known data requirement, and a clear owner.
Treat missing evidence as uncertainty rather than safety. Browser protections, network failures, and privacy controls can all reduce the available signal. Confidence should fall when evidence disappears; the risk score should not quietly improve.
Before publishing a rule, simulate it against recent traffic. Review how many sessions change, which sources are affected, and whether the result matches known outcomes. A small preview prevents a plausible-looking condition from rewriting an entire campaign view.
Finally, keep versions. When a marketer asks why yesterday's score changed, the answer should include the rule version, matched evidence, and exact adjustment. Explainability is an operational feature, not a reporting decoration.