This is something that I've noticed myself. I find that it's much easier to write a paper for school by just writing something, no matter how simple, and using it as a framework for the next iterations. It makes it much easier for me to think of the paper one piece at a time. I've started trying to apply this strategy more rigorously lately. For a four page paper I had to write yesterday, I started by just writing out the structure of the paper:

"Start with a relevant 'hook.' Now lay down your thesis statement. I got to my thesis by starting here. Then I went and saw this. That turned into the other, and here you have the thesis."

Then I took each bit and replaced it with what I actually wanted to say there and continued to iterate from there. In this case, my professor has a very specific structure that he looks for in our papers so putting that first iteration together didn't take much effort.

Similarly, when I'm working on a programming project, I find it's much easier to start with a working iteration, even by stretching the definition of "working," and improving it until I'm happy with it.

It is, of course, important to look at the paper (or other work) holistically to make sure that it all flows together once the pieces are in place.