from Nielsen, http://www.useit.com/alertbox/20020609.html
to rewrite:

Good Redundancy: Alternative Navigation Paths

One of the few cases where users actually benefit from a small amount of redundancy is in the navigational paths through an information architecture. It is not always best to restrict users to a single route to a given destination.

Consider an example task from one of our e-commerce usability studies: Visit an e-commerce site and buy a baby seat for your car. Some users might assume the seat was a car product, since they'd be installing it in their car. If so, they'd never find it on the site we tested, because car seats for babies were considered baby products and found only in that area of the site.

It's impossible to design a perfect information architecture in which all users associate each item with a single category and take the one and only true path to the destination every time. Can't be done. A few cross-reference links on opportune pages are a lifesaver and can stop garden-pathing before users give up.

Still, too many cross-references will create an overly complex interface and prevent users from understanding where they are and what options they have at that location. It's thus essential to limit cross-references to those alternatives that are both most important to users at their current location and most likely to help them overcome navigational dislocation.

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