LSAT Logical Reasoning Question of the Day

Outlining a story's plotline before actually drafting the story reduces the amount of writing time. But writing a story through free-writing to generate a first draft, which then can be reformulated through rigorous editing, produces a more creative narration of events. Therefore, when quality fiction writing is more important than generating a quick writing product, outlining should give way to free-writing.

Which one of the following is an assumption required by the argument?