One benefit of holding regular system demos is that execution can be measured across the whole ART. A system demo is a significant event that provides an integrated view of new Features for the most recent Iteration delivered by all the teams in the Agile Release Train (ART). Each demo gives ART stakeholders an objective measure of progress during a Program Increment (PI). The system demo offers the ART a fact-based measure of current, system-level progress within the PI. It's the true measure of ART velocity and progress. Achieving this requires implementing the scalable engineering practices necessary to support Continuous Integration across the ART. By holding regular system demos, the ART can evaluate the quality, functionality, and usability of the solution, as well as identify and resolve any issues, risks, or dependencies. The system demo also provides an opportunity for feedback and learning from the customers, Business Owners, and other stakeholders, which can help the ART to align with the vision and goals, and to adapt to changing needs and expectations. (Must be taken from SAFe 6 Scrum Master resources) Reference:
System Demo - Scaled Agile Framework
SAFe Scrum Master Course Outline