In my humble opinion, one of the coolest things about the Singletracks database is the ability to flesh out the amount of information about a specific trail or trail system as much as you could possibly want. Being something of a statistics geek myself, I love cataloging singletrack and adding trail information!
One of the most useful features in the database is the ability to link trails together that form a complex trail system. The Bull / Jake Mountain Trail System is a great example of this approach. This trail system is a largely self-contained network of trails that form one cohesive whole, but some of the individual trails in the trail system are radically different from others, with different technical difficulties and different amounts of elevation gain.
The best way to show the differences between these individual sub-trails is to create a trail system listing.