So, apparently this is important to writers; therefore, I will pretend this important to me because I'm discovering if I have what it takes to be a writer.
I didn't know writing methods mattered one way or another: I'm a simple girl--if I find that something works, I do it. I've been taught to use outlines to guide my work and I use them occasionally. Sometimes I don't. It's all about what works for me when I approach any particular idea.
Some ideas are complex and I have definite things I want to reveal and explore. These ideas need outlines to structure them so that they are coherent and so that I don't wander from my main purpose and get lost. For these particular ideas and stories, I have an endgame in mind. This is the destination (let's say NYC) and this is how I want to get there (by car!). Sometimes I plan out exactly how I want the story to end (Central Park on Mon, Statue of Liberty on Tues, off-Broadway show on Wed) and sometimes it's more general (shopping, eating, touring). The more specifically I plan what I'm doing at the destination, the more focused my story becomes (well, if I'm going to NYC, then I can take one of four routes). I then figure out what kind of story I'm telling, one that matches the ending (if I'm seeing an off-Broadway show, then I have to save up money and get tickets way in advance; if I'm shopping, I had better make sure that I have enough room in my suitcases and car for new stuff).
Now, I may write a slightly different plot than I had planned and add unexpected subplots to the story (detours!), but usually I'm still heading in the same direction (NYC). There may be times when I realize that the plot I'm working on doesn't fit the ending I've planned. Then I have to decide whether I will get back on track or follow the new plot (Hey,Chicago is now on my route!). I also have to decide whether what I've already written is a part of the old story if I've decided to go back to the original plot (or was I just lost?).
To tell the truth, I almost never end up where I thought I was going. But the outlines guide me and free me to concentrate on the journey. If I have an ending in mind, even if it will change, I can make my journey specific and memorable. I find that if I plan for surprises and discoveries, I find them more often.
In any case, my outlines allow for changes, and I always keep in mind that this outline is a guide not a rule. I'm not even specific with them. I'll put down "She learns a big secret" vs "She learns that her mother is really her aunt." I give myself as much leeway as I can so that I'm not burdened with trying to make a story go in a way that may not be working any more (did I mention I do what works?). I can let the characters and story build in organic ways without being confined to writing it happen in one particular way.
On the other hand, I may have a more straightforward story in mind. With these I can start with a premise and just write. However, at some point in the story I have to go back and outline to help me analyse the patterns and structures I have made. Then I decide whether I'm headed somewhere worthwhile and adjust as necessary. Making the story up as I go can feel spontaneous and thrilling, but there's a bigger chance that I will become frustrated when I suspect that I may be going nowhere at all. I like spending my time writing stories not searching for them.
Actually, I look at pantsing as just creating a different type of outline. One that is more detailed, to be sure, but just an outline that gets down specific dialogue and narration and character actions. I have to be willing to change and explore through pantsing just as much as I would through a less detailed outline.
So I guess it comes down to whether or not vivid scenes (and whether the scenes make up the bulk of the story or only a small part) come to mind when I'm working on a story. If they do, sometimes it's best to throw it all down in the heat of the moment and then go back over it and give it structure and connect the dots through a general outline.
Some writers feel that outlines suck the fun and creativity out of writing. I find they help me find it. With outlines, I can concentrate on revealing memorable characters and creating an interesting plot. It's all a matter of perspective.