How Claude Code is used in practice

This post introduces a framework for analyzing ~400,000 Claude Code sessions to understand practical usage patterns. It quantifies the division of labor in agentic coding, showing users make ~70% of planning decisions and ~20% of execution decisions. It also demonstrates that domain expertise, not coding proficiency, amplifies effective use, with experts achieving higher success rates and Claude performing more actions per prompt. The analysis shows a shift towards end-to-end agentic use and a reduction in debugging time over a seven-month period, with an estimated 25% increase in task value.