...for some writers.
For me personally, the thing I had to consciously pay attention to was novel structure. (storyfix.com was the source that finally clicked, for whatever reason.)
Between storyfix.com and
Techniques of the Selling Writer (with a side helping of The Snowflake Method), I felt a huge leap in my understanding of writing and my entire writing world opened up.
/plug
I know of writers who outline the first half of their novel. After that, they usually outline as they go, normally at the beginning of a writing session. Sometimes, if they feel bogged in the boggy middle, they'll break out the outline and work a little on it to get a sense of direction, then keep writing.
Some writers have a bare bones skeleton of an outline. The beginning, the middle, the end and maybe a few candy bar scenes and they write with an eye to hit those milestones and wing the rest, relying on their characters to get them where they need to go.
Many writers use the outline as a basic roadmap but don't cling to it with a deathgrip, realizing that in the writing of their novel, it will take them new, exciting and unexpected places...then adjust their outline accordingly.
Many writers use no outline, a basic idea of what they want to do and just go with it and write.
Many writers sit down with no idea and just write, letting it all unfold in front of them.
Some writers will outline everything and manage to stick with it.
Here's the corker. Sometimes one writer goes through all those phases, depending on the project.
One thing the finished novel has over the incomplete one: it's finished.
Frankly, it sounds to me like an incomplete outline is an incomplete plot. This is not a bad thing! But you are clinging to something that isn't working and it what may need to happen is for you to release it and try something completely different.
You know what they say about the definition of insanity...it's doing the same thing over and over, expecting a different result.