No simple answer. It depends upon the hike, the prevailing conditions, your familiarity with the area, and your experience in this environment. However, I wouldn't recommend a desert hike starting at 10 AM without a canteen(s) and water, or a start into a gathering winter storm without a good jacket and bombproof fire making capability. It boils down to - your knowledge, skill, ingenuity, and experience are more critical than any equipment.