Child, to my surprise, writes with a real 'seat of the pants' approach. He starts writing with an idea in his head, and stops when he doesn't know what to do next. He never writes a second draft. The first draft is it. With Make Me he wrote 500 words and stopped for several days. But the thing was, within those first 500 words were the seeds of the rest of the book, only he didn't know at the beginning how all those seed would come to fruition. He didn't even understand what his characters were actually doing, or who the person was that had just been killed.
There are plenty of seat of the pants writers around; most of them write a quick first draft and then go back and revise and revise, often producing several more drafts, usually with substantial changes in them. I've never heard of any other writers who work to Child's method - unless of course you count 19th writers like Dickens and Trollope, who seemed to start at the beginning and write until they were finished. (Trollope supposedly could write 'The End' to one book, and then go straight on into chapter one of the next.) But Child's refusal to rewrite anything is more unusual for modern writers, I suspect.
The other difference in his approach is his refusal to hurry. If he doesn't know what happens next, he waits, waits until he can see how things will develop. So in a sense a lot of his writing obviously goes on inside his head while he's doing other things - and this book gives the impression that he does quite a lot of other things.
I need to put things down in order to be able to think. What I put down may seem dislocated and shapeless, especially when it's in note form. I don't regard these notes as planning the novel structurally, by the way, and anyway, they often arise after I've started to write the first draft, especially when I've got stuck. But those notes usually spark off the next stage of writing.
Unlike Child, I'm not good at 'writing' in my head.