Work that focusses on internal thoughts is not well-suited to mainstream film. Additionally, if you want your film developed as a commercial Hollywood feature, it must follow a specifically structured narrative story line. This does not however mean that people talk directly about the things that concern them or the issues dealt with by the author. The presentation may be highly abstract and symbolic. Production costs limit the number of characters and scene locations.
Information is narrative.
The story line must be strong enough to carry a reader through at least 75,00O words for a hardcover book. Unlike stage or screen works, novels have no cost limitations in terms of setting or characters. Internal thoughts of both the character and the narrator may be explored in detail. This is a question most writers ask prematurely. Other than considering what kind of audience will be interested in your material, you should not focus on selling it until you have actually finished writing something.