Again, only if you leave the GPS receiver on constantly. Turn it on, mark the position on both the GPS and on your paper map, turn the GPS off. 5 minutes out of the 9-18 hour battery life typical with a modern GPS. One set of batteries can go many days.

One fix with a GPS would have shown them they were nowhere near where they thought they were located.

They would have had to rest at night so the gps wouldn't be running all the time. even hiking half the day or more will be only one set of batteries per day. I carry a dozen in my backpack so thats 6 days of constant gps use though out the day.

GPS battery usage...

I recently returned from a trip to the BWCA, where I had my GPS on all the time that we were canoeing and portaging which was 4-6 hours a day for the four days we were out.

I usually use either NiMH or Alkaline batteries and expected to need a set of batteries for each day's travel.

My canoe partner suggested Lithium batteries -- and we completed the trip on a single set.