Estimates are forecasts, not invoices. We document assumptions: integrations, data quality, approvals, and third-party SLAs.
Fixed scope with unknown integrations is not fixed risk.
Time-box discovery spikes on the riskiest unknowns—auth with a legacy IdP, payment certification, or novel hardware.
Prefer incremental milestones over one giant bang. Each milestone should deliver demonstrable value or learned constraints.
Revisit estimates when assumptions change. The goal is aligned decisions, not a number frozen in amber.
