I notice in the vast majority of themes that when you are on a post for example, the top nav has a link to EVERY category for that blog. I don't understand why that is? Often they are only somewhat related? I know it ensures consistency across the site, is that the only reason to do this? It seems like a better idea in my mind to only link to relevent categories for that post, or only link back to home (which then has all the links to all the categories)?
Thoughts? Suggestions? Concerns?