A visitor following a tag link always reaches something new of interest (don't show or don't link tags with only one item)
User story
Given that I am viewing a blog post or other tagged content,
when I press the link of a tag on that content
I want to see at least one new piece of content so that I'm not following a pointless loop back to the content i was just looking at.
Background
I've just done this enough times (and not just on Drupal sites, on pretty much every site using tagging since tagging was invented, back in the early blog era). Would be very curious if Drupal has had a solution for this though.