The main point of the Rules of Three is that we need to
concentrate on the most immediate problem first. People mainly
think of these rules for being stranded in the wilderness, but
they also apply in an urban setting, such as natural disaster,
earthquake, flood, etc. In any extreme situation:
You can survive for 3 minutes without air (oxygen) or in icy
water,
You can survive for 3 hours without shelter in a harsh
environment (unless in icy water),
You can survive for 3 days without water (if sheltered from a
harsh environment),
You can survive for 3 weeks without food (if you have water and
shelter).
Some people have suggested a fifth rule and that is 3 months
without hope.
Incidentally, if you have a stick, or knife, or any other
object stuck in you, do not pull it out. The object restricts
blood flow. Wrap the area around the wound and seek help as
soon as possible.