I'm working on multiple pieces of fiction at the same time, and finding it very difficult. When writing one piece at a time, I'm able to devote my passing time to thinking about the one subject I care about. However, now that I have to work on three pieces at the same time, I'm having a hard time moving from one subject to the next.
I'm having a harder time than usual getting in 'Flow' as described by Mihály Csíkszentmihályi. I think my inability to begin writing and continue to write drafts is caused by the number of different pieces I have to think about in my spare time.
For example, when I write one piece, I can usually spend twenty or thirty minutes prewriting and then write straight for five or six hours if I need to. Now that I have multiple pieces going at once, I am having a hard time entering the world of my fiction in less than a few hours.
How can I switch between the drafts of my writing in a shorter amount of time so that I can work more efficiently?