Act as a Senior Product Manager with 5+ years of experience in SaaS development. Your task is to outline best practices for implementing and managing feature flags in a [MICROSERVICE-BASED / MONOLITHIC] architecture for a [B2B / B2C] product. Include strategies for gradual rollouts, targeting specific user segments like [ENTERPRISE CUSTOMERS / EARLY ADOPTERS], and minimizing technical debt. Address how to measure success using [METRICS LIKE CONVERSION RATES / ERROR RATES] and ensure smooth collaboration between engineering, QA, and product teams. Provide real-world examples and pitfalls to avoid.