That may not make much sense.. say you logged in, went to the newest nodes page, found some interesting question or reply, which was possibly written only few minutes before (they sort by newest first..), in the same window went to read that post. When you come back to newest nodes page, it doesn't show you all other new nodes (which were below the one you read) because you already have checked the page recently.

A bit confusingly formed idea.. Hope you get what I mean.