Thesis: I think people are overusing Google+ circles and it's having a strong negative impact.
TL;DR - stop posting stuff to specific circles and start posting stuff to all your circles or even public
For most of the time I've used Google+, I've used their circles system pretty heavily; car article go to my car nuts group, recipes go to the foodies group, etc. I'm going to stop doing this soon and there are three primary reasons why I think Google+ circles are (in most cases) a bad idea:
1. It assumes I know all the interests of all the people in my circles. This is patently false and if you think it's true then you are a liar liar pants on fire. At best, I maybe know a handful of interests of a handful people in my circles. I could have friends who are thinking about getting into cooking and I'd want them to read the New Yorker article I shared about why cookbooks are problematic but I have no idea what that person is thinking.
2. It has a hugely destructive effect on the crosstalk of ideas and knowledge. I love watching TED talks because it's a bunch of people from a broad range of disciplines coming together and exchanging knowledge that wouldn't have happened otherwise. New, creative, innovative ideas are really just existing ideas from disparate areas mashed up in a different way. If you only share stories with people who already have an interest in the subject, you prevent the information from being passed on and used in a new way.
3. You think that your feed is great because everything in it is stuff you like. But what you don't notice is that you're insulated from different points of view and it becomes a self-affirming cycle that doesn't include disagreement, debate, and discussion.Your reality is never challenged and you never have to process anything different. As the speaker in the TED video says, it shows you what you want to see, not what you need to see.
Don't get me wrong, there are definitely some awesome uses for circles: group projects, planning a pub crawl, sharing pictures from a party, etc. But for the most part, the general sharing of stories and thoughts, limiting that information to a specific subset is a bad idea in my opinion.