One of the things that I always need to work on once I get a first draft done is pacing. I don't worry about it in a first draft--I don't worry about much of anything in a first draft--but once I start revision, I can always always condense two or three or half a dozen scenes into one. For example, this is what the scene outline would look like for the current draft of the TNP:
scene 2, which takes place 1 hour after scene 1
scene 3, which takes place 1 hour after scene 2 and in which the character tells a new character what happened in scene 2 and/or scene 1
scene 4, which takes place a week after scenes 1-3 because I've skipped all the "boring" parts like the subplot and any relevant descriptions, and also back story and plot.
So you can see I always spend a lot of effort working on the pacing. In a very early draft of The Book (which now takes place over the course of about a month), the action took SIX MONTHS, which doesn't sound like that much time, except a lot of it was "montage" writing, the literary equivalent of the training montage in Rocky III or the college montage in Spiderman 2 (or, heck, name your montage). A few drafts later I was all "hmm...maybe I could just get rid of the whole two and half months when NOTHING HAPPENS." Revision: it is my friend.
Now, some people would say that if I were better at planning upfront, I wouldn't need to do so much revision with regard to pacing. They would be right. If I outlined, or "broke story", or whatever cool techniques you can read about on the internet to structure a story, I probably could save myself a lot of time revising to make the timeline fit and to make sure that I didn't have a lot of dead space or redundant scenes. But I would also probably have never finished a single story, because all that structure is boring!
Don't get me wrong -- it's super important that, in the finished product, each scene adds something to the plot and/or the characters. Every scene must be meaningful.
But for me, part of the joy of writing is just starting and seeing what happens. To follow the path of the story. In the TNP, for example, I have a complete first draft except that there is only one plot point to the whole draft, so when you read it you think "doesn't this kid have any interests except X?" Well, of course he does, and I, the author, know all about them. But I sort of fell in love with this storyline, see, and wrote all of that part first and now I have to go back through and thread the story with the rest of the stuff that I know about him, which I would do in the first instance in a bunch of unrelated and awkward scenes that aren't related to the other scenes, and then, finally, I will start to see how they fit together.
For me, pacing is like putting together the pieces of a puzzle. "Oh, this scene doesn't go here, it actually gets turned upside down and goes there!" That's kind of what I enjoy about revision, actually, is the feeling that all the pieces are there, and now it's up to me to get them into the right order. It appeals to my organizational impulses as well as my creative side.