I think if you wanted to truly implement some type of functionality like this, time on site could be a component. It would definitely filter out the case of so

I think if you wanted to truly implement some type of functionality like this, time on site could be a component. It would definitely filter out the case of someone like me, who clicks through to the comments and then clicks the story link in the comments. I do this so my browser history points back to the comments when I'm done with the article. I have no idea how many other people do this.