1. Sometimes publishers ask for a detailed outline, so it is good to have one.
2. An outline will help you to visualize your novel as a whole.
3. An outline will prevent you from skimming through your entire novel to find "that one part."
4. An outline will help with your timeline and continuity issues.
5. An outline will help you with your story arc.
6. An outline will help you with your character arcs.
7. If an outline reads boring, your story is probably boring.
8. An outline helps you to see which parts of your novel need more suspense or detail.
9. An outline will help you with your pacing.
10. Whether you write the outline before you write your novel (Plotter) or after (Pantser), it is a useful tool for editing and polishing.
Helpful links for how to outline a novel:
I Write, I Edit, I Write Again. Witness!
We're Making Better Words, All of Them, Better Words.
I Write to Burn Off the Crazy.
A Good Day Writing is a Day Writing.
It Puts the Words on the Page or it Gets the Hose Again.
Just keep writing...just keep writing...writing, writing, writing!
Writing is Magic.
The First Rule of Write Club is You Talk About Write Club.
If You Aren't Writing, You Aren't a Writer