I do not think the concern is so much whether the training is using choker chain or not. If the dog is not pulling or taking you for a walk instead, one can do without a choker chain. Mainly the choker chain is for beginners who find their dog unmanageable. Some training that I know of uses the normal collar. But do ensure that your collar is not too tight or too wide. Our weather is not so suitable for it. Basically that's the reason most people prefer choker chain or none at all.
Yes, the choker has to be put on correctly 'p' and will loosen if the dog does not pull you. The other way around 'd' will not loosen if the dog pulls and then stops pulling. It is also made in the instance that the dog is meant to walk on the left; put on correctly; and will loosen completely when the dog is not pulling.
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