Contrary to what is commonly thought, humidity is a really secondary factor with crested geckos. I had cages which I NEVER sprayed at all, I just left a water dish in them and kept the substrate slightly moist, that is all. In other cages, I would spray about twice a week. This made no difference for the geckos: no shedding problems, no dehydration issues, all of them were well regardless of how high the humidity in their tank was -and that was done over many years with a subsequent number of animals. You know, their native habitat and the precise spots where they are found is not as moist as one would think. And I have never trusted hygrometers, feeling they were more misleading the user than giving proper info.