Given a large analytics query, refactor it to minimize table scans. 1) Replace unnecessary CTEs that cause multiple scans with inline aggregations or derived tables where appropriate. 2) Prefer GROUP BY aggregations when applicable and justify the execution plan. 3) Explain how you would verify the number of scans using EXPLAIN and iterate on the plan. 4) Start with a quick draft solution, then refine it to reduce scans and improve readability.