There was no such thing (defined) as ADD back when I was in my youth, but I realize I have something akin to that, which is why I tend to multitask even when there's no good reason. For me, I like to have several things I can switch between when I feel frustrated or bored with one particular thing (story) I'm working on. At the moment, I have at least three things I'm working on, which I move among as the mood strikes. I find that for me it's good to have "away time" from one particular project when I hit a spot where I don't feel like working on it perhaps due to some issue that needs resolution or possibly just burnt out having my mind run on the same track too long. I doubt I'm the only one who is like this, but I suspect I my "method" is not too common. I end up with a lot of unfinished projects, for sure, but on the other hand, I never lack something to do when I want to play at being a writer.