The UPS Route is aptly named as a route, rather than a trail, because there is only a vestige of where to walk. Hundreds of cairns mark the way down the route, but many of them are misplaced which then leads a hiker in the wrong direction or down a more difficult lead.
The numerous cairns are not really needed but they do help a hiker not to have to choose the way, but rather, allows one to somewhat hike on "auto pilot". That allows the hiker to focus on foot placement as one descends the jumble of rocks, boulders, and ball bearing-like gravel in the talus filled chute. The first 6/10 of a mile drops 1600 feet. Of course, with all the zig-zags you make you will be walking much farther than a mile down the first two chutes to the bottom of Bedrock Canyon.
You can view this and many other panoramas of the Grand Canyon at GCPano.org where you will find more detailed descriptions along with topo maps and interactive movement from one panorama to the next.
GCPano.org