From an interview in Co.create:
Whedon advises getting the fun stuff done first. “Some people will disagree, but for me if I’ve written a meaty, delightful, wonderful bunch of scenes and now I have to do the hard, connective, dog’s body work of writing, when I finish the dog’s body work, I’ll have a screenplay that I already love. I used to write chronologically when I started, from beginning to end. Eventually I went, That’s absurd; my heart is in this one scene, therefore I must follow it. Obviously, if you know you have a bunch of stuff to do, I have to lay out this, all this dull stuff, and I feel very uncreative but the clock is ticking. Then you do that and you choose to do that. But I always believe in just have as much fun as you can so that when you’re in the part that you hate there’s a light at the end of the tunnel, that you’re close to finished.”
The whole interview is here.
I do work from an outline, but I go through and write the scenes that have me on fire first, then connect and re-arrange them later.
If you write, do you write beginning to end straight through, or in scenes you go back and connect later?