Personalized Notification System

Netflix has developed a hierarchical framework for its personalized notification system, separating long-term strategic decisions from real-time tactical execution. This involves a 'Slow' policy that creates a personalized weekly messaging plan for members, considering long-term engagement and potential fatigue, and a 'Fast' policy that handles immediate send decisions within those strategic guardrails. This decoupling allows for independent optimization of pacing strategies and message selection. This post details the evolution to this hierarchical architecture, highlighting the 'Slow' policy's role in defining personalized pacing and the 'Fast' policy's role in maximizing immediate relevance, communicating via a low-latency feature store. Key results include significant metric lifts, particularly for casual viewers, and the ability to iterate independently on pacing strategies and ranking models.