Loren Brichter is an app developer, he made the Letterpress app, & was the developer:
...to create or help popularize app features such as pulling on a touch screen to refresh a page, panels that slide out from the side of a screen and the "cell swipe," which is swiping to uncover a list of hidden buttons.
In an interview this month he had this to say that caught my attention, in italic:
Do you mostly focus on one project at a time, or are you a multitasker?
I’d describe my work schedule as cooperatively single-threaded with a heavy context switch cost, so I try to keep time slices on the order of about a week. So I have lots of projects going at once that usually relate to each other in some way, but I only consciously work on one at a time.
I can’t consciously multitask at all, but I think my brain works a bit like libdispatch. The subconscious can chew on a lot of stuff in parallel. So when my conscious mind switches back to some other work it put aside earlier, there are usually a couple good ideas waiting for it.