Hardware metaphors

Computer metaphors do not always work well in real world.

Here's an example of a metaphor that produces good results when transported in life: RAM vs. permanent storage. Each productivity system (e.g. Getting Things Done) worth its salt recognizes that our brains have limited RAM and we cannot keep in mind too many things at once. But we can use what is called an exocortex - an extension to our brain to augment our capabilities - namely, the Internet, but even a sheet of paper where to write our calculations, or diagrams.
One of the uses of the exocortex is storage: a simple paper notepad that is always with you will be able to function as an hard disk, and your brain RAM will be freed and available for other purposes. The point is not only to avoid forgetting an idea or a TODO, but to avoid worrying about forgetting at all.

Here's an example which doesn't work. Real time notifications are more and more embedded in our system; the sources of input are instant messaging system like email and Twitter. Technology does wonder: compare snail mail to an email being delivered in seconds.
Yet we find ourselves avoiding the wonderful technology of real time communications: interruptions are considered a menace for our flow and our Pomodoros. In order to get large batches, I visit GMail only few times a day, and I'm working on lowering this number; I avoid any kind of GMail or Twitter applet in my panel (although they may work for managers: I'm talking about creative work as put in danger by interruptions).
Polling is often a waste of CPU cycles for computers, and in fact they are built from the ground up on an event-based model: hardware interrupts. Yet the model fails miserably when, due to the inability of humans to multitask like a machine.