Last-click ROAS quietly distorts most accounts: it over-credits the channels that harvest existing demand and starves the prospecting that creates it. Worse, it says nothing about margin or cash. The right north stars are CAC, payback and contribution margin.

Give each channel a role

Google captures intent; Performance Max and YouTube extend reach; Meta is your scale engine, powered by creative; LinkedIn is precise B2B account targeting. Trying to make every channel do everything is how budgets leak.

The four efficiency levers

Account and audience structure (where most waste hides); a structured creative-testing pipeline; landing-page CRO; and a measurement stack you can trust, sense-checked with incrementality on your biggest lines.

Scale without wrecking efficiency

Expand deliberately — widen audiences in steps, keep fresh winners flowing, and protect payback as the guardrail. Scale is earned by the system, not forced by the budget.