This is a good topic, but the focus is too limited. Backbreaker or money maker?
Walking a trapline is certainly a good healthy activity. It will make you tired, but it’s not “back breaking”. The problem is, you just can't cover much ground. However, you can learn vastly more about the critters by a walking trapline than you can by any other means.
I suspect almost every beginning trapper starts out with a walking trapline, and that’s a good thing because it really heightens your learning curve. But by the time you gain some proficiency, and if you really want to try to make a little income from trapping, you are going to need more territory than you can cover on foot.
But just because a walking trapline doesn’t pay in fur, it still has value in exercise and recreation. You don’t have to be a “long linger” to be a trapper.