CBO vs ABO: ABO wins testing, CBO wins scale

CBO vs ABO: ABO wins testing, CBO wins scale
Across 50 accounts, 90d:
— ABO (ad-set budget) in testing: 22% lower CPA on new creative — equal budget per variant gives clean reads
— CBO (campaign budget) at scale: 15% lower CPA above $3k/day — Meta shifts spend to winners faster than you can
The failure mode: CBO in a 4-ad-set test dumps 80% of budget into one set before you have significance. You learn nothing.
Read: test with ABO for clean data, scale with CBO for efficient allocation. The tool follows the job stage.