structure versus narrative flow

Think about it in terms of building a mall.

You create the floor plan, set up your retail outlets, food court, comfort rooms, theaters and so on. You also make plans for how you intend the traffic to flow - placing elevators here, escalators there, and so on.

When you open the mall to the public though, traffic determines its own course. People may eschew your elevator and take the stairs or not find a store or avoid a floor or just hang out in an unintended place you did not plan for. Or it may work perfectly, with traffic moving in, through and out with satisfying precision.

When I think about structure in terms of writing, I think about the general architecture, which includes elements like just what form it will take within the context of the story's demands. That should determine the flow but sometimes it doesn't (writing is like that, sometimes what is predictable refuses to behave - or you exercise will to alter its predictable behavior).

When I consider how I will work in terms of the narrative flow, I do the equivalent of a "soft opening", see if the flow I had in mind reaches the places in the structure I want to reach. If it doesn't, then I tinker either with the flow (easier) or the architecture (disheartening). Easier with the flow because it becomes a matter of trying out variations. Disheartening with the architecture because its more fundamental and supposedly you made a right call. Whatever.

Normally though, the structure (if well-planned) takes care of the flow, unless you deliberately wangle with the flow for effect or to move your agenda.