ALWAYS prepare for the worst. By failing to prepare, you are preparing to fail...and failure in this case could be death.I don't necessarily disagree with this sentiment, but try going 50+ miles off pavement in the middle of no where in Utah or Nevada during summer and break down without water, food or a way to keep cool. Plenty of people have died in Death Valley due to this exact sort of mistake (including many who have driven onto 4WD roads without the right vehicle).
Yes, in most cases you may luck out and have someone else come along who can help you or be able to get back to somewhere with a cell single or a bit more traffic, but you may be walking 20+ miles in some pretty bad conditions. You should be prepared for the worse in most cases, especially if you are messing around in sub optimal conditions.
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