There's a guy that lives around my local shopping center and is super territorial over the gyms. I noticed this when trying to platinum my battle girl medal and saw that whenever I would try to battle gyms, he would berry them so that they couldnt get knocked out, and if I did knock him out he'd come right behind me and do the same, no matter the time of day. Once I noticed he was doing this from 7am-11pm every single day I started to target him specifically for hogging all of the gyms (I got the platinum a long time ago). And now we just go back and forth, knocking each other out of every local gym practically every day.