How Come?

A friend is going on a tough deployment for the U.S. Army. He is incredibly well trained. What's he doing? Training and training. And then training.

I acknowledge the Army situation is about life and death. But it is also a "profession."

Why does the Army, from recruit to general, train and train—but, mostly, the private sector does a smidgeon of individual training and virtually no unit training, let alone combined unit training?

(What would happen, for example, if you were a retail store owner, and were open one less day than normal each week—and devoted that full day you were closed, with full staff, yes, once a week, to training of various imaginative—and boring—sorts?)