If you look at coral cats in the wild, they have a rather small range per animal. Once they find a spot, they tend to hang out in it, and use it as a type of "operation base". They'll venture out for food, but return to the same cave or crack to sleep and just hang out when not hunting.
I'll go out on a limb and say the 'smallest for them vs largest needed' could be quite close in size. As an example of that, we've got a nurse pup in a 250,000 gallon. 99 times out of 100 I can tell you within two feet of where that animal will be without even looking. He has his established spot, and stays there. From what I've seen with coral cats under my care, they behave the same way.