Some writers sit down and write a novel chapter by chapter to the end. Some writers find this discipline difficult to achieve and may never write their novel because of it.
An alternative to chapter by chapter is to write individual scenes that could be placed somewhere in the novel. By a scene, I mean a moment of dialogue, a dramatic or adventurous event, or anything representing a unique segment of the story.
The scenes do not need to be in any specific order in the story. Nor do they need to involve characters. They can be long or short and do not need a beginning or an end. There is only one requirement.
Scenes should contain some type of an “arc” meaning a rise in action or dialogue, the climax, and an aftermath. The arc does not need to be dramatic, but the climax should be some important knowledge revealed or a change in a character or environment. After writing several scenes, the writer fits them into the story like puzzle pieces.
To create a flow and link the scenes, beginning and/or ending sentences may need to be rewritten. Mostly, the writer needs to create connecting passages that lead from one scene to the next. These passages should not have an arc, but give the reader a rest between scenes. As an example, they can show people moving across a landscape or thinking about what happened or setting up for the next scene.
Writing scenes provides freedom to change the story as needed by moving the scenes around to where they belong best. The writer will not see the story as a whole by looking at scenes, yet when put together they have a novel.