A dog's size, temperment, and attitude are key in deciding if a choke chain should be used at all in training. It is my opinion that there are some dogs that not only do not need this device, it should not be used on them, ever. That said, this is a highly effective training tool that can get the attention and control of the bigger, stronger, and more assertive dog. There is one correct way to use a choke chain and various incorrect ways. One needs to be certain to use the correct method in order that the training tool is effective and not harmful to the dog. It is of the UTMOST importance that you know the right way to make a "correction" with the choke chain. I would never leave a choke chain on at any time other than a training session or walking.

There are a lot of dogs that cannot be controlled or trained without this device. I use it occasionally myself and know that with Hannah, one or two "corrections" immediately reminds her how to walk on a leash and who is in charge when we are walking. The alternative would be her pulling on the leash and gagging herself on her regular collar for the duration of the walk. For a larger dog the choke chain as a tool for control can be even more critical.
It is an asset to many dogs and their owners.