Not all writing need be entirely coherent. The stream of consciousness is not just for artists. It's just you don't necessarily want to share the stream of consciousness if you're an academic. You may profit from writing it.
I like the ability to just get my ideas down quickly; to skip from one thing to another; it allows covering a lot more territory. Something is often lost in the process: a suggestive line or two, written in the moment an idea is flush, may not be so suggestive when you go back to read that note some time later. Many a brave idea has met its demise in this fashion at the hands of my memory.
Incoherent writing is easier. perfection unnecessary; punctuation can drop by the wayside. I personally like punctuation because it helps me express my thoughts. Some people think it's a nuisance. If you're writing for yourself why worry what others might think?
Practice is important. writing--when ever, how ever--is a practice. Today's stream of consciousness cuts a path for tomorrow's eloquence. Or at least entertainment from the act. Yesterday I wrote about running. You've got to practice a little to be able to enjoy acts. some days going for a run seems really hard. And some days so does writing.
Writing doesn't seem easy to me. Day after day it requires effort. But I keep practicing to develop a better relationship with it. It doesn't necessarily seem easy, but it gets easier with time. Especially if I don't worry so much about what I'm saying.
We could be digging ditches, struggling to make ends meet, or maybe cleaning other people's houses. It would be a challenge to turn such situations into transformative growth. Dissertations have a lot of difficulties. Writing in general has a lot of difficulties. Writers have their troubles and toils. The dissertation, for all the heartache, has a real chance to be a transformative experience. All the hostile, selfish, petty, close-minded people who try to interfere can't take away that opportunity. One of the things that makes dissertations so difficult is the extent to which the writer is left alone--but that also leaves the writer the opportunity to grow into his or her own maturing voice.
Random jottings of thoughts, late night whimsy and early morning optimism, even that letter you've been meaning to send, can be part of a practice of putting your thoughts onto paper. And that practice will accumulate, day after day, into a skill. Some of those random jottings might even turn out to be something about your dissertation that you can use. It would be nice to have such things pile up, day after day, too, no?