11am US Eastern time appears to be (on average) the busiest time for Twitter. In this one minute sample (12/13), there were a total of 269,396 tweets. This includes all publicly available tweets and retweets. This does not include users that are search banned and dark tweets.
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Must be when everyone's scheduled tweets go out. I wonder if tweeting at 10AM would make your content have more visibility since the 11AM deluge could easily drown your content?
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