I couldn’t help myself, I turned around and said—"A good product manager keeps the Story Map in play." His response was, “We don’t build products we just work on projects.” To which I confidently replied, “Your projects are your products.” But I digress.
The short answer to is a product ever get to a done point is both yes and no. In technology a product is only done when it sunsets. As long as there is ideation, research, iteration and upgrades the product is not done. So the question is really more of progress to go live. This is true regardless of implementation methodology.
There is a role on the team that keeps an eye on releasing the effort and that is the product manager. A good product manager—gets the whole team involved with the effort at Sprint 0. Sprint 0 is when the team comes together and works with the story map. The story map is the visual display that aligns strategy, user needs, and stakeholder needs.
A story map's the holistic view of the user experience throughout the whole journey. The Release Plan for sprints develops out of the story map and UX determines its pace to code build at that time as well.
Priorities shift, requirements change, and iterations happen. The product manager keeps pace and grooms the priority backlog. Without the phase 0, UX, and the Story Map, agile can become short sprints working on a set of ever-changing priorities. A little like riding a roller coaster that never ends.