Part of it is structure, breaking a story up into sections - earlier today I was reading a story by Aurelie Catena, with a series of escapology challenges, each written as a separate chapter. In my case, chapters are more about releasing work earlier rather than waiting months or even years for a complete story in one go - and I like to get feedback and tailor future chapters based on how earlier developments were received and any requests from readers. Sometimes I get stuck on a particular plot - as with 'Flashbacks' - then reader feedback can steer me to develop the next instalment in a particular direction, or even come up with an idea for a new character or development I wouldn't otherwise have thought of.