I follow the same routine as Pat and Lisa. DAHPP (no lepto) and rabies every 3 years, separated by 3-4 weeks. Lepto is a more common reactive vaccine, and doesn't cover everything anyways. Bordatella doesn't last long, doesn't cover everything, and isn't as serious. Lyme is not a huge concern, although some of the lure fields I go to have lots of ticks. Corona is not necessary either.
I prefer to keep things to a minimum. I would strictly do titres if I could, but one of my clubs/organizations does not allow titres at this time. I stay away from training facilities that require whopping combos of shots, I don't feel that's good for my dogs. Responsible owners are what will keep your dog healthy, not crazy shot schedules. I don't board, but anyone who does will probably have to get bordatella unfortunately. I have traveled across a good portion of the country with my dogs and have done quite a bit of competing at all different kind of venues. I have never had a problem with any of my dogs, even though we've been in some pretty tight quarters before with other dogs. The only thing I've ever had to deal with was a little giardia that I probably got from back home on the farm. lol
Like others have said, some vets are slow to change over to 3 year vaccinations, but all US Veterinary Colleges have now adopted the 3 year rule. And almost all states have gone to the 3 year rabies. There is currently a 7 year rabies challenge study going on. I know quite a few people that have older dogs who have been titred and never needed another shot since their 1 year puppy booster. The vaccine is exactly the same whether it's 1 or 3 years. And same amount, no matter the size of dog. (it's not like wormer) I see several places charge a different amount for the 3 year, probably because they won't get your money the other two years. lol
The low cost vaccine clinics are probably fine, they would be using the same vaccines. They just aren't going to give your dog a good looking over first, and it's not a good idea to vaccinate a dog who isn't feeling up to par. So if you're only vaccinating once every 3 years, no reason not to get it done at a vet check-up. However when you space out the shots, the 2nd one could be done at a cheaper clinic, just keep an eye on their location/cleanliness. Or spread them out, do rabies one year and distemper the next, so they never fall in the same year again.
It's amazing what over-vaccinating can do to the immune system.