Learning how to choose between CBO and ABO for better ROAS depends on your campaign maturity, audience size, and conversion volume. CBO excels when you have sufficient daily conversions (typically 50+) to give Meta's algorithm meaningful data for optimization, while ABO works better for smaller budgets or campaigns requiring strict control over individual ad set spend. The 2026 landscape shows that CBO campaigns achieve 15-25% better ROAS on average when conversion volume supports algorithmic learning, but poorly-configured CBO setups can waste budget on weak placements. Media buyers must evaluate their current performance baseline, test both approaches in parallel, and monitor which structure delivers better cost-per-result within their specific vertical. Implementing the correct budget strategy can unlock 20-40% efficiency gains within the first 30 days of optimization.