I do not take a compass on backpack trips anymore, except if I am in terrain that is rolly hill or flat. Between the sun, stars and my maps I really do not need a compass in the areas I travel.

But here is one use of a compass. For those of us who are more graphic than number people, you can line a map up visually with a compass. You do have to dial in magnetic declination, but that can be done at home. Set the compass on the map legend and just line up the magnetic north arrow on the map legend with the compass needle. It is very simple. Of course this only works if you have bothered to use a real USGS map or printed a legend that includes the little picture of the true north/magnetic north arrows.