I have this basic test that I apply before I add a feed to my RSS reader.<p>I arrive at some site by way of a link. If the story is good enough that I think I want to read more by the author, that's exactly what I do. I click the 'previous' link. If the author is good enough that I want them to show up in my feed reader, chances are I'll keep a tab open for days while I read through their old posts.<p>When I reach the start and I still want more, that's when I click the 'add' button.<p>I don't know how well this applies to news blogs, but that's what things like Hacker News are for.