For greenfield tasks constructing one thing new, you possibly can iterate rapidly. Mistaken assumption? Rewrite it. Missed a requirement? Add it subsequent dash. The price of errors is measured in developer time and missed deadlines.
For legacy modernization, errors compound otherwise. You’re not simply constructing new performance. You’re changing programs that course of payroll, handle stock, deal with monetary transactions, route customer support calls — crucial operations the place “oops, we missed a enterprise rule” isn’t acceptable.
Conventional modernization approaches tried to unravel this by way of huge requirements-gathering efforts. Armies of enterprise analysts documenting each display, each workflow, each edge case. These tasks took years and infrequently failed as a result of by the point you completed documenting, the enterprise had advanced.