In large-scale programmatic campaigns, marketers blend deterministic and modeled audiences to maximize reach, relevance, and performance. This approach requires a clear framework, continuous measurement, and disciplined governance to avoid overfitting or waste. By aligning data assets, technology capabilities, and creative strategy, brands can scale precision while preserving efficiency. The balance hinges on the predictability of first-party signals, the adaptiveness of probabilistic models, and the realistic expectations for attribution across complex funnels. With disciplined experimentation and transparent reporting, advertisers unlock consistent lift without sacrificing privacy or consent considerations.