ABO for testing, CBO for scaling.
ABO (testing phase, 2 to 4 weeks): a fixed budget per ad set, so every creator and asset gets guaranteed spend and clean, comparable data. No creative gets buried before it has had a fair chance
CBO (scaling phase): one budget at campaign level that the algorithm distributes in real time, for a lower blended CPA over time
The sequence: start with ABO to test every creator and asset fairly. After 2 to 4 weeks, identify winners, pause underperformers, and consolidate into CBO. Let the algorithm scale what the data has validated.