I would never leave home without it. It is best to buy it at the time you buy your airline ticket.
A lady on our tour of Israel died on the 1st day of our tour before the bus left the hotel. The insurance paid for the body to be prepared for iternational transport back to the states. Reimbursed her husband for all expenses incurred for the tour including airline tickets...cost of tour etc. Also paid for the son (who lived in Tel Aviv) to ecort his father and mother's body back to the states.
All this for the $139 for the cost of the travelers insurance. Well worth the price.