You seem to confuse the creative process with the final product. The rules can change during the creative process. It's the final product that I judge as a reader - I won't bother going over the inconsistencies in Harry Potter here, it's been done ad nauseam elsewhere. The physics doesn't change over the course of the story of the Martian.
What you view as inconsistencies are based around assumptions for how the underlying rules work and what happened that don’t necessarily apply.
One of the more interesting science fiction short stories I read seemed to have very inconsistent time travel, but on closer reading you find the two different methods involved had two different sets of rules. It’s easy to say something is inconsistent, but any possible story has a corresponding set of rules that work.
It’s rather similar to considering what characters may have been lying in a story.