Yea well I feel like a blue footed booby.
But now to begin with a ridiculously out there way to explain how I got that measurement. Ok so if you have two females, so split the cage in two. But one is going to be dominant over the other in some ways. So she will control more then the other. So she will control 40% of the cage. They will share 20%. Add in wasted space of a large pot, corners, and the bottom of the cage and you have a total of 70%. So that is how I got 1/4th the volume.
But that is all an excuse and I was just stupid with math. Still funny tho.