It doesn't take long for an intranet to outgrow a single portal page. Once there's too much content to fit on the page, the portal has to expand to multiple pages. Each subsequent page represents a logical 'chunk' of the intranet content and functions.
The initial page serves as a top-level directory, giving direct links to the most important content and helping employees hone into the subsequent pages specific to the chunk they need. Employees use the design of the initial page to quickly eliminate unlikely choices. The page's design must clearly communicate what is found in each of the chunks.
Each of the subsequent pages expands on the major chunks, allowing users to see more of the picture of what the intranet holds. This is similar to zooming into a map to see individual streets, where only major highways were visible previously. It's important that enough information is presented at these lower levels to ensure the user is confident with every click.
Scent teaches us that the most important content needs to be nearest the top of the hierarchy. The best designed intranets have clearly identified those content and functions that employees need and represent them with very clear scent in the portal.