I struggle a bit with the crested gecko group myself. It seems to be very "all or nothing." For instance... it is impossible to keep more than one crested gecko successfully together. It does not work. They will die horrible deaths. And yet... I've done so several times in the past with females and it was okay. My personal favorite piece of knowledge they spread is relating to caging. According to the crested gecko FB group, an 18" square ExoTerra can BARELY hold one crested gecko... and it's absolute cruelty to keep a crestie in such squalor. They feel that an 18"x18"x24" ET is the minimum for an adult crestie. And that will only hold ONE crestie of course.
I just bought an 18"x18"x24" for my new day geckos and it seems overly large for two of them. I cannot imagine only housing one crestie in it. What a waste of space. My smaller females and adult males do quite well in 12"x12"x18" vivs, and my largest female is happy in a 20 gallon. But perhaps it's because my geckos don't have a FB account and aren't "enlightened."