Why it matters: You can’t redesign the product’s navigation and information system every time new features or content arises. Navigation menus and product's overall layout must support new categories/topics without breaking down. Under 'room for navigation growth', we mean that your major design and development efforts should be easily scalable across the interface.
How to test it: Male sure to discuss with your stakeholders the possibilities of content growth: will you have more static content? does your architecture need to support videos? And lots of other related questions.