Budgeting 3–5% of infra for trace storage (e.g., Langfuse). Model Drift: Recalibration time for evolving AI APIs.

Use the Estimate Accuracy Ratio (EAR) (Actual Hours / Estimated Hours). A healthy target is 0.9–1.1 . 3. Leading Estimation & Management Tools

Every credible estimate is a range, not a single scalar. An "initial idea" estimate typically has a range of 0.25x to 4x , narrowing to ±10% only after a detailed technical spec is signed.