I find it difficult to focus on one project at a time. I can manage for a week or so, but I will eventually get distracted by something else that's shiny. While I've been frustrated by this for a lot of my work life, I'm finally beginning to accept it, and learning how to control it.
For instance, I will tell myself, "I'm going to write to this part in ________ project. And then I'm going to this other project." For the past two months I have been doing this, and working on a kind of carousel, and it's been working great. Let's face it, I have a short attention span (don't we all?) and that's the only way I think I can work now.
That's another reason I am into the "mini books" now. I need to build these novels in increments, or otherwise I just can't handle it. In setting small goals, in both writing and publishing, I'm hoping to be more productive.