If a person lives in a warmer climate that it is really hard to cool animals in, it might be advantages to brumate animals together. I was using a frig to brumate a few years ago, and obviously was very limited on space. I brumated my males by themselves, but brumated the females communally. I had absolutely ZERO problems doing this and recommend it to people that may be limited on space for brumating. If you know your animals and they are healthy going into brumation, then there is no problem with this. Also, note that I did not brumate males together. Competition between males, during brumation, could prevent one or more of them not performing during breeding season.