If I see 3+ posts from the same username within the same minute, every one of the posts I see gets downvoted, and you and the instances get blocked.
I just leave my feed on All to see a bit of everything, but it drives me nuts when I see someone either post the same link in quick succession to 3+ instances at the same time, so they all end up next to each other on my feed, or you post several related posts (photography, articles etc) within a few minutes so your name and all...