We built a RAG system for one of our clients in the aviation industry. >20m technical support messages and associated answers / documentation, and we're seeing between 60-80% recall for top 3 documents when testing. Definitely pays off to use as much of the structure you'll find in the data, plus combining multiple strategies (knowledge graph for structured data, text embeddings across data types, filtering and boosting based on experts experience, etc). The baseline pure RAG-only approach was under 25% recall.