Recognising creative fatigue before the cost-per-result tells you

Frequency and engagement-rate decline tend to signal creative fatigue before cost-per-result moves visibly, because platforms initially compensate for declining engagement with adjusted delivery before the cost impact becomes obvious in the top-line number.

Tracking frequency and click-through rate trend alongside cost-per-result, rather than cost-per-result alone, gives an earlier warning that a creative refresh is needed — often a week or two before the account-level numbers would have flagged it.

Refresh cadence should be set by category and format, not a universal rule: a narrow, high-frequency retargeting audience fatigues creative far faster than a broad, cold-audience awareness campaign reaching new people continuously.