It would never work for me, though. I can't imagine how spending 15 min/day on a screenplay would be productive at all -- when I sit down to program, or write, it takes me that long just to "restore state" and remember what I was in the middle of previously. I only really find myself becoming productive at things after the first hour -- plenty of people call this being in the "zone", etc.
This might be a good thing to do with fairly menial/brainless tasks, but is it really useful for more than that? But even with cleaning the house... it seems so much more efficient to spend an hour every week, when you've got spare time, than vacuum a room and a half one day, dust half the house the next...