When I had a BCI as a kid, all I did for humidity was have a water bowl and do a daily misting in the screen-top aquarium I used for it. Never had an imperfect shed.

However, both times Ippo shed while I've had him were perfect sheds. All I do is have a waterbowl and moisten the substrate whenever it looks dry.

Then again, I probably live in one of the most humid places in North America so that may have more to do with where I live than how I care for my snakes.