Facebook & Meta Ads
ABO
Ad Set Budget Optimization — you assign the budget to each ad set individually instead of to the campaign.
ABO (Ad Set Budget Optimization) assigns the budget to each ad set individually instead of to the campaign, so every ad set gets exactly what you fund it with. That manual control is useful on microbudgets, or when you want to protect a specific test from being starved by the algorithm's allocation.
We reach for ABO when budgets are tight and each hypothesis needs equal money to get a fair read; on larger tests we default to CBO 1-3-3 and let Meta distribute. Structure is not the lever, so do not expect ABO versus CBO to fix a weak creative or a broken funnel. Once an ad set catches the spark-up, duplicate the winner rather than nursing the split.
In buyer speech
“Run it ABO first so each creative gets a clean $20 — I don't want CBO dumping the whole budget on one ad set before we've read the others.”