Writing SQL queries is straightforward, but creating a reliable system for running them efficiently is complex and often results in poor data quality and operational inefficiencies. Transitioning from ad-hoc scripts to a structured, spec-driven architecture enhances reproducibility, validation, and observability of SQL jobs, ultimately leading to better management of data and costs.

• Ad-hoc SQL scripts scale poorly because they lack reproducibility, validation, and observability, leading to silent data quality issues and wasted compute costs.
• Moving to a spec-driven architecture (defining queries as versioned, declarative configs rather than one-off scripts) makes jobs testable, auditable, and easier to rerun consistently.
• Centralizing query execution through a structured system enables built-in validation and monitoring, catching errors before they propagate downstream.