That section is really badly worded. There is continual disagreement as to whether a "feeder" includes a feeder from the main panel to a subpanel. (It seem obvious to me that it doesn't, but there are many who are of the opposite opinion.)
On the theory that this section is all about load diversity in a residence, it seems to me that Table 310.15(B)(6) should apply to individual USE conductors in the service to a single family home. They have the same advantage of load diversity as a service entrance in a single cable or a raceway.
[This message has been edited by SolarPowered (edited 04-29-2006).]
