Some people like to work on one project at a time, seeing it through to completion and then starting the next one. While focusing on one thing at a time can be an effective way to work, there are many advantages to thinking about your writing as a funnel:
______________________________ (here's all the ideas for projects you have)
_________________________ (here are the projects you're collecting research on)
___________________ (here are the projects you're drafting)
___________ (here are the projects you're revising)
___ (here are the projects you're submitting)
One nice thing about the funnel is that when you submit, you can always turn your attention to the revisions you need to make for the next thing, which keeps you from agonizing about the article or chapter you just send off, as Dr. Clay Spinnozi pointed out in our publishing workshop. You are always submitting because you are always writing!
Another advantage of the funnel is that you know what your next project is instead of casting around for ideas. You might consider writing down all the ideas you have at the top of the funnel somewhere. This is especially nice when you're revising your dissertation: keep a list of ideas for the book version, and you can cut them from the dissertation without feeling bad.
Now not everyone is as easily distracted as I am, but I personally really enjoy being able to shift between the projects in the funnel. "A change can be as good as a rest," as my grandpa used to say. When I'm burned out from revising an abstract theory-heavy section of a chapter, I can move to the more concrete practice of coding responses from another project. If I just can't outline a new chapter right now, maybe I can edit the bibliography of an article. If I sit down to do my sustained writing and I just really don't want to do one task, I can coax myself into writing by beginning with another task *
* This task has to be in the funnel, though: writing long comments on a YouTube mash-up video or crafting the perfect response to a Facebook argument doesn't count.