I am definitely a writer that plans. I write extensive outlines, draws (terrible) maps, writes out pages of floating dialogue, etc.
(evidence of my terrible map making skills and my outlining which is literally just paragraphs of rambling text)
I like to word vomit, essentially. My outlines for a 50k novel tend to be at least 2k if not longer. Then, as I begin to write, I'll add more to the outline, including notes for revising later. Because, if NaNo has taught me one thing, it's a lot easier to finish a first draft if I'm not constantly backtracking and editing as I go.
(behold the tiny white board that accompanies me in my writing nook)
Honestly, there is only so far ahead that I can plan. About one month ahead is going to be fairly accurate. Two months becomes dodgy. By three months, my plans will probably change.
The reason I do all of this, dedicating time to planning and writing outlines and preparing, is because I always strive to be a consistent writer. I named this blog 1000 Words because that is what I try to write every day. Even if that writing is outlining, or blogging, or scribbling on my white board with as many colors as possible.
I feel like every writer has a different method to their art. The details of each method really aren't important. Whether there is planning or no planning, an outline or just an idea, it doesn't matter. What matters is that we all actually manage to create something we are proud of.