I agree with that sentiment. Every few months when I have some down time, I go through each feed and toss ones that are posting too much. It also allows me to toss ones that I added because they had an interesting post 3 months ago, but had crummy follow-up posts that just clog up reader since I do not read them.
I recently instead made a personal rule to just use google reader for blogs that don't post heavily, usually ones curated by a single person.