Optimizing for 'Purchase' on <50 weekly sales is why your CPA won't drop

Optimizing for 'Purchase' on <50 weekly sales is why your CPA won't drop

Meta optimizes toward whatever conversion event you pick — but it needs volume on that event to learn. Pick one too deep in the funnel and you starve the signal.

Weekly purchase volume vs CPA stability (90 accounts):
— 50+ purchases/wk: optimize on Purchase, CPA stable
— 15–50/wk: CPA swings ±35% week to week
— <15/wk: never exits learning

Fix: low-volume accounts should optimize on a higher-funnel event with 50+/wk (Add to Cart, Initiate Checkout) and use value rules to bias toward buyers. Move to Purchase optimization once weekly volume clears 50.

Read: an algorithm fed 8 data points a week isn't optimizing — it's guessing with your money.