First, how humid does the room tend to stay from day to day? What's your local climate like? Do you measure the humidity level in the cages and what do you use to measure it? All these things can affect whether you need a humidifier or not. You may only need one in some seasons (such as winter when you have to heat your house more). If you find that spraying multiple times of day is keeping the cage humidity level where you want it to be, fine. If the cage is sitting too dry for much of the time, am automatic misting system or room humidifier can really help.
There are three types of humidifiers...a vaporizer which creates steam from boiling water. Often used to loosen kids' congestion. This isn't what you want to use as it will heat the air, could scald plants or your cham, and as the heated water cools it can stagnate fairly quickly. An evaporative humidifier blows air through a wick that's saturated with water. The wicks need to be replaced regularly and they can also mold. A hassle. An ultrasonic humidifier is the type that produces a fine mist that's about room temp. IMHO these work the best for a cham cage. The ultrasonic type is sensitive to mineral build ups on the nebulizer disk, so if you have hard water you'll need to clean the deposits off regularly. Not hard to do with vinegar.
A misting system isn't the same as a humidifier. A misting system will produce larger water droplets more like rain, not fog.
