Recently I found myself hitting the "mark all read" option in Reeder (iOS) and ReadKit (OS X). When staring at an unread item count of several hundred, it's easier to do that than trying to catch up. I realised that I had less time to read the "feeds". Some feeds had less compelling content than I had thought, and many had stale content. Some feeds posted news almost as fast as it happened, often with little analysis and insight. So why read them?
Earlier this week, I switched1 from FeedWrangler to Feedbin. The Feedbin feed management tab allows me to sort my feeds by the name of the date they were last updated. I had a lot of feeds that had not been updated in several months, and some of the sites were no longer online. I got rid of everything that had not been updated in two months. Some sites may not update often but have excellent content. But thirty days is a good cut-off point.
I also got rid of any sites that were too "spammy". I had some sites that had several updates every fifteen minutes2! And many of those posts are just short one-paragraph links to longer articles on sites I already followed. I got rid of the "dupes".
I am now able to find more wheat than chaff in my feeds. I am hitting the "mark all read" button a lot less.