The mission of an RTE is value delivery. They guide the train to move on the right path from the beginning till the delivery. System thinking plays a significant role in making this happen. We have to think about teams, about the fact that some do not deliver value, and RTE needs to understand the entire flow value and know how the value stream is working and where the value is flowing. It means that their focus needs to be on identifying bottlenecks and being conscious of handoffs and dependencies between teams. An RTE is the kind of person who can put things together and has a systemic view.
There is another aspect associated with this - cadence and synchronization - RTE needs to establish and manage it between the teams. And the last element is also related to the roles consuming the work that ART generates. The value delivered to someone, and that someone needs to be well informed. And RTE should focus on this. Stakeholder management is the keyword in the previous point. The focus here is on optimizing the whole system rather than individual parts to deliver value to the organization.