Why are phase-gate Milestones problematic?

Phase-gate milestones are problematic because they often use documentation as a proxy for solution progress. This approach assumes that completing certain documents or passing through predefined gates accurately reflects the progress of the solution. However, in Agile methodologies, working software is the primary measure of progress. Relying on documentation can lead to a false sense of security, where teams believe they are on track based on completed paperwork rather than actual working software. This can delay the discovery of issues and hinder the ability to make necessary adjustments in a timely manner. SAFe Scrum Master Reference SAFe Principles: valuing working software over comprehensive documentation SAFe 5.0 framework: the drawbacks of phase-gate milestones and the emphasis on iterative progress with working solutions