I'm back a day and half early from my 80 miler on the Tahoe Rim Trail, due to the excellent construction of the trail system, ultralight gear, and wanting to get back to my family. I averaged 23 miles a day and witnessed a courteous mingling of mountain bikers, day hikers, trail runners and only a few backpackers mostly camped at popular sites. I had many hours of solitude hiking each morning - plenty for me. The problem with this trail is running back into some type of civilization about every 20 miles. In between those times, there is a lot of "wilderness experience" to be had with spectacular views. I was pleasantly surprised.
The TRT is unique with mostly non-designated wilderness, but it offers modern lessons in how to manage wild areas. The areas I went through were managed by a variety of agencies. The TRT Association, and others in this half of the trail - especially Nevada State Parks, have invested in facilities, signs, and information boards at each major trailhead, and a wilderness campground with a new water pump, bear boxes, tables, and Oh My God, toilets. The only litter I saw on the trail was a laminated fishing regulations sign (CA DFG) that fell off the tree it was nailed to. The take-away lesson I see is that people respect nice facilities that are maintained. If society is willing to invest in such things, people tend to respect it and are more likely to pick up after the losers who would ruin it. Time will tell if the maintenance investment will continue, but the concept is clear to me. Simple education is also a key factor and should not be downplayed. It means a lot more when it comes in the field than by being forced to sit through an office lecture or slideshow.
After reading the papers posted by Dale, one conclusion is consistent in each document: trailhead quotas are not a standalone solution and should only be used where necessary in conjunction with other management strategies. Other factors are equally or more important in determining the quality of a "wilderness experience."