SEK on signposts

Sarcasm aside, signposting is very useful. It's better to include a lot of very obvious signage in a first draft, then revise to make the signage more implicit, the transitions more seamless. You can tear down the scaffolding after the building is built, but you keep the structural beams. There is a dimension of signage which is mostly useful to the writer, while writing, and another which is mostly useful to the reader.

Scot also points to another function, which is to fold (seemingly) extraneous material into the argument. Here you will need a sign that says, "Scenic Detour This Way," but also The Detour is Really Relevant Somehow.