Having been in the military, I can testify that one of the things military planners obsess about is a real emergency occurring during an exercise.
Confusion is guaranteed, like a real fire breaking out during a fire drill. This is why the military rarely advertises alerts unless it's at the last minute (so no one will be able to plan an action during the exercise) or in areas where civilians can get tangled up in a free-fire zone (as in naval exercises).

Being from Tampa (where MacDill AFB is CENTCOM HQ) we all knew when an alert was being called because half the workforce (moonlighting airmen) would have made arrangements to have that day off. A sudden increase or decrease of air activity over S Tampa was another dead giveaway.