Maybe if you go in circles. If you cover 20 miles/day, even in places like Alberta or Wyoming, it's hard to go much more than two days without bumping into another one in one form or fashion.
For example, this woman died after weeks spent lost just near the Appalachian Trail: https://www.bostonglobe.com/metro/2016/05/25/hiker-who-died-...
When I was a kid, we were amazed at the people who apparently got lost on Hell's Half Acre, about 40 miles west of Casper:
- https://www.google.com/search?q=hells+half+acre+wyoming&num=20&source=lnms&tbm=isch&sa=X&ved=0ahUKEwi2iqHTsOXPAhWCsFQKHegtCo0Q_AUICCgB&biw=1151&bih=818
Now that I'm officially old, and far less energetic, I'd be willing to believe that they just sat down and hoped that help would find them in time.