Reading Usable Help
@UsableHelp on Twitter
Gordon R. Meyer
Designing for information shoppers
A link at InfoDesign points to a great overview of information access and heuristics by Whitney Quesenbery. If you've ever wondered why many help systems seem alike, always providing a table of contents, a Find command, and an Index, you'll discover your answer here.
My opinion is that the desire to serve as many "information shoppers" as possible leads to this usual mixed bag of usage models. And as the old expression goes, a jack of all trades is a master of none. It's refreshing to find that a few instructional designers are willing to buck the trend and create great solutions for one or two models, rather than mediocre solutions for many.