Every prospect call starts the same way. They tell me Performance Max is "underperforming" or "going up and down" or "spending the budget but not converting." Before I quote a number, I open the account and run this list.
1. Conversion goal hierarchy
Open the account-level conversion settings before you do anything else. PMax bids against whichever conversions are marked Primary. If "Add to cart" is Primary alongside "Purchase," you're optimising toward carts.
2. Asset-group structure
One asset group per campaign is fine for a small catalogue. It's a problem the moment you have meaningfully different products or audiences.
The net of the audit: if an account fails 6+ of these eleven checks, the right move is rarely to "tweak" — it's to rebuild.