This works great if you're plugging away on an existing system, knocking off bug reports. But it doesn't work at all for prototyping cool new stuff on a clean

This works great if you're plugging away on an existing system, knocking off bug reports. But it doesn't work at all for prototyping cool new stuff on a clean sheet of paper. Ingenuity and Ticket Systems don't combine very well. There's no list of action items for Truly Cool Stuff. You just dive in and start messing around. You can probably externalize some context as you cross off ideas and concepts that won't work. But there's no game plan, thus no concept of a "Next Action". You're on a blank sheet of paper with a head full of context, and any distraction will kill that. So yeah, there are circumstances where you can survive interruptions. But there are also circumstances where they'll kill you.