I am following over 400 twitter accounts.
Many are people I know, some are well known people I don't know and some are news channels and the like. If a real person follows me then I will follow them back. Seems like a common courtesy. 400 is probably at the low end in the number other people follow. When I see accounts that follow tens of thousands I suspect they are not reading all of their incoming tweets. In anycase my 400 produce enough tweets to keep me occupied.
I think on a normal working day I might be able to 'read' about 500 tweets, including the occasional longer read. This includes the time I spend on the train going to and from work. On a less than normal day I might get to 150 tweets and and on some days, like today when I am not at work and not particularly occupied, I might 'read' all of the tweets in my twitter stream.
I have a few strategies to help me manage my stream of incoming tweets.
1) I maintain a private list of those people whose tweets I don't ever want to miss. This includes immediate family. This would be less than 100 tweets a day. I can manage that on any day.
2) Some people I follow are heavy tweeters and from time to time I will mute them. I don't want to unfollow them as I see conversations that involve them in the interconnected flock of mutual friends, but I can't cope with their volume. Also they follow me and I just don't unfollow people who have the done the courtesy of following me.
3) I will mute hashtags even if I am interested in the conversation but just don't have the time. A recent library conference was a good example. Tweets with well formed hashtags are my friend. Tweetbot lets me mute a hashtag and remove already loaded tweets from my current stream. Nice.
4) Sometimes I just have to let it go. I'm the sort of person who has no unread email in their email - I don't just mean in my inbox, I mean in my mailbox (I have seen people with a thousand unread emails in their inbox but that is topic for another post) - and I'd prefer to read all my incoming tweets. But sometimes you just have to let it go.
5) Lastly I do some housekeeping from time to time. This means unfollowing some accounts but not people I know or who follow me. Unfortunately I also tend to add accounts from time to time. Lots of interesting people and things.