Information can be organized in either flat or deep hierarchies; both have their advantages and pitfalls.
Should your website’s hierarchy be flat or deep? Like most design questions, there’s no single right answer, and going too far to either extreme will backfire. Flat hierarchies tend to work well if you have distinct, recognizable categories, because people don’t have to click through as many levels. When users know what they want, simply get out of the way and let them find it.
But there are exceptions to every rule. In some situations, there are simply too many categories to show them all at one level. In other cases, showing specific topics too soon will just confuse your audience, and users will understand your offerings much better if you include some intermediate category pages to establish context.
Observing your users—via usability testing, analytics, and search logs—can help you understand what problems your audience needs to solve, and how familiar users are with your content. This background knowledge is essential to achieving the right balance between a breadth and depth in your hierarchy.