In winter, I would be lucky to make 48 hours. In warm weather I could probably last a week. Grabbing a blanket, knife, water bottle, and hat on the way out the door would delay the inevitable by a few days.
Anyone thinking they could survive easily needs to remember the survival Rule of Threes:
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3 minutes without breathable air (unconsciousness), or in icy water.
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3 hours without shelter in a harsh environment. (Including sleeping outdoors uncovered on a cold night, IMO.)
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3 days without drinkable water.
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3 weeks without food.
Dehydration will get you faster if you drink contaminated water from a stream and pick up giardia or some other infection that causes diarrhea.