Our groomers and our boarding kennel both accept the yearly one rather than the every six month one.
But if you give it yearly, you are ONLY giving it to placate the boaring kennel gods. Because no Bordatella vaccine is really effective for more than 6 months. Then again, they are also only effecrive against a fraction of the strains of bordatella out there, so the vaccine is no guarantee that your dog won't get Kennel cough.
IMO, bordatella vaccine is protection for the kennel/groomer (so that when someone comes in saying their dog has kennel cough, they can look totally surprised and say, "Well, he COULDN'T have gotten it here... We require that ALL our clients vaccinate against it").
The only good thing about it is that it does seem to be one of the more benign vaccines... Causing less problems than many. So it mostly hurts your pocketbook rather than your dog.
Among the show and performance sport people I know, who, in general, are the MOST careful people about the health of their dogs... KNOWING that they are regulary in contact with or near many other dogs, I don't know any who are willing to give Bordatella vaccine to their dogs.