Sorry for not finding your message sooner.

I have no idea why others may house their Rubber Boas individually. When I use to maintain a fair number of the species, I always had specimens of like sizes housed together.

In the wild, it is more common than not to find two or more boas together under cover objects. About two or three years ago, I recall finding 8 male boas under one piece of roofing tin that was bout 16 inches square.

Richard FH