i know it’s recommended to keep leachianus in groups because of how social they are (could be a very cool idea for your tank if you can source them) and i admittedly figured the same could be done with all new caledonians since most geckos seem to do good in groups. keeping multiple specimens of most things together in the reptile world is kind of a taboo so i think thats why people say not to do it. i keep my leopard geckos together even though its often advised against. it usually comes down to multiple reptile specimens cant be kept communally if theres a male in the tank.Just about everything I’ve read (including a reptile forum I’m on) says that cresties can only be together if breeding, very occasionally does it go otherwise. Gargs are the same way. I’d assume other rhacs would be similar.