Actually, I think some Blackheads can reach 12ft or more and I’ve heard of some 9ft Womas in Australia, but I believe the typical Woma in the US won’t get much bigger than 5 or 6ft. You probably already know, that although rare, Rainbow Boas have been known to reach 9 ft.
I understand that an active snake needs more room than an inactive one, but it makes no sense to me to say that you could keep every Rainbow Boa in a 3 ft cage and you need at least a 4 ft cage for every Woma. I will say that a typical Rainbow will do fine in a 3 ft cage. I don’t have any experience with Womas, but the ones I’m getting are maybe 3ft long now, if and when they out grow their 3ft cages I’ll gladly move them to larger ones, I’m just not convinced that I’ll have to.
Dan