Ham radios aren't the great emergency radios seen on TV and in movies, just like it's unlikely to be able to shoot from the hip and kill all your enemies with one shot everytime. Propagation varies from various parts of the 11 year susnspot cycle to another, seasonally winter/summer, day to night and even minute to minute. The unpredictiblity is what makes it interesting, challenging and makes it into sport.
Like WRQC527 says, it's tricky (but fun).