Humidity: How low is too low?

[Lefitte]

So one of the reasons I chose a California Kingsnake over other species was because they are found in my area in the wild which meant that the general conditions would be easy to manage. Summer still hasn't lost its grip on us yet though and it's been into the 100s with humidity in the high 20s. During summer, we regularly get humidity levels in the single digits so I have to ask...

Outside of shedding, is there any reason to worry about keeping the humidity the recommended 40-60%? I know the problems it can cause when the snake is in shed but will it cause any problems when she's not actually in shed? I was able to keep the humidity up just fine for her shed last week and had no problems with it at all.

I don't want to raise the humidity too much, I know that can cause problems with the one functioning lung and all, but should I bother to get a moist hide when the humidity is this low but she's not in shed?