[bryanlarsen]

Many, if not most, jobs have a peak utilization rate well below 100%. The most obvious example is fire fighting. IIRC, a firefighter should spend less than 10% of their time fighting fires. If they're spending more than that, then they're likely to be busy when you need them.

Sure, they're likely to spend a good chunk of the other 90% working, but it's just busywork. That busywork might be important: they spend a lot of time inspecting and maintaining their fire trucks, for example. But it's not their "real job". Their real job is to be close to the fire truck so that they can respond when an alarm rings.

It's much the same for the rest of us, except that the line is grey, not black and white like it is for firefighters. We have a priority list, and stuff on the bottom of the list will never get done unless it bubbles up in priority for one reason or another. That stuff at the bottom is real work, but since there's always stuff that's more important it's comparable to "washing the fire truck".

And even the stuff at the top of the list is busywork in a way: it's always possible for more important stuff to come in and bump it out of the way. A server can go down, or an important customer can call, or ...