What is one problem with phase-gate Milestones?

Phase-gate milestones are traditional project management mechanisms that mark the end of one phase and the beginning of another. One major problem with phase-gate milestones is that they assume a point solution exists and can be built correctly the first time. This assumption does not account for the iterative nature of Agile methodologies, where solutions are developed incrementally and iteratively, with feedback loops and continuous improvement. Assuming a point solution can be finalized early often leads to rigidity, lack of adaptability, and higher risks of delivering a product that does not meet the actual needs or expectations.