Well, used to anyway. Most of us can handle three or four projects at one time by alternating our attention from one to another. But Mother Nature built in some real limits to our marvelous capacity. Move that phone number to 10 or 12 digits, and watch people do a stutter step as they scramble for a piece of paper to write it down. Our need for order and priority is so strong that we will create our own if it is not otherwise available.
Most people react to uncertainty in pretty predictable ways.
High levels of uncertainty usually hit us very hard. While personal strength and stamina may vary somewhat from individual to individual, most of us have a limited amount that we can bring to bear in a work situation. We can get in better shape and eat more nutritious food for added energy, but even that cannot add 10 or 20 hours to our productive work week for the long haul. If you have read this far, you already know the point. And, while most of us can handle a 50-hour week, we can't handle 60 or 70 hours week after week.