Writing is not always mechanical, nor is it always something that is amenable to a fixed structure.
But sometimes, perhaps even many times, it is. And game writing is technical writing for the most part, and that means structure, clarity, and ensuring the right information is conveyed.
For the Tower of Justice scenario I’m finishing up right now, that means that something was missing up until today. And thanks to a timely brainstorm over on the GURPS discord chat, that thing which was missing was a certain “be sure this information is in each part of the scenario” structure.
Things are going very well now. The organization ensures that each piece of the scenario will get equal treatment on paper, rather than easy treatment and improv in my head. Nothing wrong with improv! But if you’re buying a scenario, it’s likely because you want the bases covered for you so you either (a) have a good basis by which to improvise, or (b) don’t have to improvise in the first place.
In any case: structure is good. Having one means you know what you’re leaving behind when you break that structure, too.