I’ve probably already had this discussion with my regular readers, but I find it interesting so it’s worth having again.
The other day I was reading a book about essay writing and the author said that you should have a minimum of three drafts before your final paper. Until last year, there was always a part of me that thought I must be doing something wrong because I never had several distinct drafts of a paper before turning it in. Not until last year did I realize that it’s just that my writing style is different.
I tend to revise and edit while I’m still writing the essay. So when I get to the end, it’s usually pretty close to being final. I don’t have multiple, distinct drafts. That’s not to say that I don’t make changes or corrections after that point, just that they don’t tend to be very significant.
So I’m wondering, what is your writing style? Do you write your whole paper/essay/story and then go back and edit and revise and then do that multiple times until you reach the final product? Or are you like me, where you make tiny revisions and improvements while you’re still working on the “first” draft?
A Moment Worth Living 
I think writing and rewriting is so individual. It really depends on the writer’s level of skill.
Some writers like to write everything they can think of and then go back and revise. Others review each page and change it before going on.
It seems common to recommend that everything has to be revised several times over. But I think that advice comes from people who see poor writing so often they assume everyone needs to revise several times.
I did read an interview by a screenwriter recently who said that he reviews each day’s output and makes changes as he goes so that by the time he finishes it’s final. I’ve also read stories by authors who rewrite 8 -10 times.
It seems to me that those who use an outline rewrite less than those who just start writing without one.
I revise as I go.
Academic Papers and in general:
1) Like you, I correct as I go.
2) I write my introductions first. That’s wrong, I’m told. The intro helps me track how the body paragraphs should be, just as an outline would.
3) In the conclusion, I sum up based on how the body paragraphs actually turned out.
4) Then I rewrite the introduction, read through again, and make mostly minor changes.
Fiction:
1) Rules 2-4 apply.
2) I do make minor changes as I go, but I take notes about major changes. When I finish the first draft, I go back and reread before applying any major changes.
3) I bulk it up with backstory.
4) I then ruthlessly attempt to shrink it by removing unnecessary scenes, paragraphs, and words.
I always write intros first too. Like you, I use it as a sort of outline. I don’t think it’s wrong if it works, you know?