What is the best measure of progress for complex system development?

 The system demo is the best measure of progress for complex system development because it provides an integrated, comprehensive view of the new features delivered by the Agile Release Train (ART) over the past iteration. The system demo offers the ART a fact-based measure of current, system-level progress within the Program Increment (PI). It also allows the stakeholders to give feedback on the solution’s fitness for purpose and alignment with the vision. The system demo tests and evaluates the complete solution in a production-like context to receive feedback from stakeholders, including Business Owners, executive sponsors, other Agile Teams, development management, and customers (and their proxies). References: System Demo - Scaled Agile Framework, Principle #4 - Build incrementally with fast, integrated learning cycles - Scaled Agile Framework