As Sharon pointed out in her comment yesterday, writing a novel as a collection of self-contained short stories creates a double constraint. On the one hand, each short story should stand on its own, which means it should possess some kind of plot movement and resolution, as well as characters who, within the context of the individual story, fit the modest goals of that story.
At the same time, those characters need to have a deeper existence, with larger plot and character arcs that come into focus only when one reads the entire collection of stories.
In a way this is a bit like the constraints of ambitious writers of episodic commercial television, as seen in the work of Joss Whedon and his collaborators on “Buffy the Vampire Slayer”. You can tune in and watch a single episode and be entertained — a practical requirement for commercial television. Yet you would then miss the real power of the series, since its most compelling aspects arise from the fascinating relationships between characters that form and evolve over the course of years.
The nearest equivalent I can think of to this double constraint within the world of novels is the episodic work of an author like Charles Dickens, who was paid to write his novels in the form of monthly or weekly installments within popular journals. It is plausible to conjecture that the publishers of these journals expected any given entry to be a self-contained entertainment in its own right.
Unfortunately there is no easy way to ask them about this.