there is no need to keep it constantly damp for youR BP, your plants may be a different story idk. I let mine dry out for a bit before I spray it down to make it damp again.

However, a constant very slight dampness, as far as my research has shown, should not create scale rot. If it's too damp, like towards soggy, then it can happen. I'm not an expert tho.

remember this tidbit though, depending on what kind of hide you use, the humidity may be well above what it shows in the tank itself.

The uth evaporates the water in the substrate and I know that when I would spray too much and focus on the tank humidity, even when the substrate outside the hide was totally dry and my tank would read 45-50% humidity, inside his hides would still be damp with quite a bit of condensation built up inside of it.

It is a glass aquarium though that can't hold humidity well at all, and I use a CHE so of course this all depends on your individual set up and how it reacts to everything. But keep in mind that where he/she spends 90% of its time may have different moisture levels Than the rest of the tank.