It's extremely dry where I live and spraying doesn't do much. My house's humidity is usually around 25%. I used to have a BP and I tried the wet towel thing, spraying with water, moving him away from the window, but it was always around 50%.
What substrate??
The key time is shedding time so spraying a few times daily as soon as the eyes clear results in perfect sheds in my experience.. mine are heated by flamin ceramic lamps which are a nightmare as regards humidity