If you are panicking at every bump in the night, and every shadow, you are too worried. If you realize, on a cognitive level, that bad things CAN happen, that is appropriate.
Anyone who said a disaster of the scale now facing Japan was impossible, has been proven wrong. Countless thousands of people now dead were wrong when they thought “this person really can’t be that creepy; they can’t be thinking THAT”.
Churchill was right in taking Hitler at his word; Chamberlain and most of Britain were wrong. Those who said Lenin then Stalin then others had built a slave state based on forced labor, mass imprisonment, torture, and murder were right; those who denied it were wrong.
The proper use of perception is determining first what is possible, which is a VERY large category for people with any imaginative capacity at all, then what is LIKELY. Anyone who uses their perception properly will regularly find themselves in error, and make corrections making similar mistakes less likely in the future, if not impossible.
To imagine the worst possible is not at all the same as EXPECTING it. In my view all Americans should have at least one week’s worth of food and water, multiple flashlights, first aid supplies, and some means of defending themselves, preferably a gun. This is a basic list, to which much can be added.
To prepare for natural or “man-made” (that euphemism continues to astonish me in its brazen contempt for the reality of the situation) catastrophes does not require you to dedicate time each and every day to worrying about them. Worry is wasted energy. Thoughtful preparation is not.
If that guy across the street creeps you out, then listen to that instinct. That does not mean that all people walking the street at night are potential criminals.
I have recommended often the book “The Gift of Fear”. I think all women, in particular, should read it.
Perfect perception would consist in always doing just the right thing, just when it is needed, in furtherance of long, medium, and short range goals, which in our perfect formulation, will line up like the rings Odysseus shot through in the Odyssey. Self evidently, the smartest of us have our heads up our asses half the time (please note that to fail to perceive something you should see is a species of idiocy), so doing pretty good is the best most of us will get. Even Sherlock Holmes made mistakes, if you read the actual stories.