Is a shock Collar necessary for training the dog ?

A shock collar is a new advancement in dog training methodology. Loads of people swear by it when it come to training their dogs. The mere thought of an electric shock evokes scary thought in our minds when it comes to us. But since it is on the dog, we only care about is the outcome of a well trained dog, which at all is also not a surety.
Is it necessary to subject your dog to such a cruelty ?
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