DinoInDisguise
A russian spy disguised as a t-rex.
This assumes that the purpose of all RPG is the generation of coherent narrative, which as you say Narrativist system handle structurally. That simply isn't the case. I don't know how to explain that more clearly.
I think this is a misunderstanding here. Even in games that aren’t focused on coherent narrative, the core point still applies. This is because pacing matters in any playstyle.
Just because a game isn’t telling a structured story doesn’t mean it’s doing nothing. There’s still player engagement, tension, momentum; and those all benefit from good pacing.
So even in your example, every roll should have meaning. Rolls that do nothing, are, in my opinion, wasting time. The presence of a narrative is kind of irrelevant to the larger principle, good pacing matters.