Sporkasia - If you watch TV, you have probably seen fire sprinkler systems coming on and various people getting soaked with water. This happens enough times on TV that you think it must be common. The truth is that sprinkler systems rarely go off for no reason. I don't know the percentage, but if a system activates then smoke, fire or intense heat are probably near by.
Sitcoms and detective pictures are not the best way to learn about fire protection. Watching fictional TV can give you a distorted perception of fire protection products.