RE: What is the most effective training method?
About the only instance I can think of where keeping a dog in a kennel would be preferable to having it as part of the family (for training purposes) might be in the case of training an American Field horseback All-Age pointer that would be expected to run a mile or more out in front of its handler in the quest for gamebirds. Sometimes, keeping these dogs in the kennel makes them that much more " rarin' to go" when they are finally let out.
However, I personally know for a fact that at least one of the finest trialers of this type in the nation let their champion setters come in the house. They also hunt wild birds with these same All-Age dogs on foot.