Once per few months I do a total clean up of email newsletters I'm subscribed to. Same I do with followings on Twitter. It has no particular timeslot in my calendar and happens when information flow becomes unbearable. A good indicator is having a fear of missing something important. We start spending more time reading feeds and have to enable notification for particular people. Otherwise, they get lost in the endless content flow.
This flow acts like a snowball. You discover interesting people and interesting newsletters, they recommend/like/retweet other interesting people and you follow them one by one. It's good for discovering useful stuff but easy to overdo and overflow your feed.
I've tried using lists and thoughtfully picking newsletters to follow. The content in my feed getting better each time, but after some point, its amount grows back. I've started to ask myself "Why do I chase the content?", "Why do I fear to miss something important?", and "What is important in the first place?".
Sometimes the abundance of information has a negative effect rather than positive. On the internet, you can look for the content you need without relying on a chronological feed. You can discover interesting videos, articles and essays without chasing the updates and without the fear to miss something. But for some reason, we often forget about that.