CAC drift on Meta

Anomaly Hunter flagged the cause on Sunday night: the L3% lookalike audience hit 6.2× frequency, breaching the 5× threshold. CAC on that audience is up 18% over the period, dragging blended Meta CAC up ~$340. Pattern matches January's fatigue spike — back then frequency climbed to 8.4× before we paused and CAC peaked at $1,850. We're not there yet but the trajectory is the same shape: +0.4× per week on the frequency curve. The recommended move is a two-week pause on L3% specifically (L1% and L2% are inside thresholds at 2.4× and 3.7×), which gives the audience refresh time and avoids the deeper CAC spike that January's late pause produced.

L1% has the most headroom — current frequency 2.4× against a 4.5× ceiling. The Revenue Optimizer's pending proposal is to shift $8K from L3% to L1% on a 30-day window, then re-evaluate. L1% marginal ROAS is 3.4× vs L3%'s saturated 1.9× — so even with a one-for-one shift the CAC on that $8K improves materially. Projected impact: blended Meta CAC drops back to the $4,900 baseline within 10 days.