Ideally, with the detailed architecture blueprints and content mapping complete, the production process would proceed smoothly in a paint-by-numbers manner, and the architect could sit back and relax. In reality, you must be actively involved to make sure the architecture is implemented according to plan and to address any problems that arise. Why? Because you're human. No architect can anticipate everything.
Many decisions must be made during production. Are these content chunks small enough that we can group them together on one page, or should they remain on separate pages? Should we add local navigation to this section of the site? Can we shorten the label of this page? During this phase, be aware that the answers to these questions may impact the burden on the production team as well as the usability of the web site. You need to balance the requests of your client, the sanity of the production team, the budget and time-line, and your vision for the information architecture of the web site.
You should not need to make major decisions about the architecture during production. A significant investment has already been made in a particular direction. Discovery of a major flaw in the architecture at this point is an information architect's nightmare. Fortunately, if you've followed the process of research and conceptual design before production, this is unlikely. You have worked hard to define the mission, vision, audiences, and content for the web site. You have documented the decisions made along the way. You have resolved the top-down and bottom-up approaches through content mapping and detailed blueprints. Through careful planning, you've created a solid information architecture that should stand the test of time.