I wanted to add a brief comment on this.
Most trappers only expect a 1 in 10 capture on snares, In other words a 90% failure rate.
This is with people who are familiar with their terrain and their game.
The results become much worse for people not practiced in the arts of trapping or familiar with the area.

The main uses of snaring and trapping for a survival situation are:
a) Positive mental attitude. The person has something to keep them occupied and gives them the feeling they are doing something positive to help themselves.

b) Setting up and checking a small trap line pins the person to their location. They are not wandering off and getting even more lost.
This is a very useful thing for the SAR team.
It is easier to find a wrecked vehicle than a person on foot.
Also useful is the lost person keeping a decent signal fire going at night.

edit:
One other thing setting a small trap line does is increase your situational awareness of resources in your area. You will be looking for things within a short walk of where you are and will likely find other useful stuff. (Water sources, fire fuel, building materials, sheltering spots or plant foods.)