[ctdonath]

Every methodology fails from pretty much the same reasoning.

The saving point of Agile is breaking tasks into reasonable sizes, long enough to actually get something done and short enough to rearrange as needed sooner rather than later, and to delay interruptions until they can be evaluated and other tasks completed. I can't get to what I need to do if the relentless onslaught of self-important "do this _now_!" interruptions are handled as they occur; Agile provides a sane way to say "get in line" such that important issues are addressed in a timely manner relative to other issues and without compromising other stuff that also needs doing (those that never reach the top of the interrupt stack, but without which long-term progress won't happen).