Jan
It is confusing isn't it. I have done a lot of reading about annual boosters and the risk they carry. I will keep this short and I stress this is the conclusion I have personally come to, based on the information I have found. Others will have their own opinions/beliefs.
Over vaccination carries a great risk of the animal developing auto immune disease (I lost one of my cockers to it). Research seems to show it is OK to have the primary vaccinations at 8 weeks and 12 weeks of age, followed by a booster 12 months later. After that, is has been suggested that no more boosters will be needed throughout the rest of the animal's life as they will have their own immunity to the diseases. This can be confirmed by having the animal Titre Tested (a blood test which determines what antibodies the animal has against parvo, hepatitis and distemper). My own vet will Titre Test for me but at a greater expense as I am the only client asking for it, at least at the moment. If my cocker has antibodies, he won't have the vaccination. If he doesn't have antibodies, then he will.
Of course, if I go down this route and it is found that Toby has antibodies and is not vaccinated, I won't be able to kennel him or claim off his insurance for any disease he may develop which he is not vaccinated for.
It's up to the owner what they decide to do but if you can read up about it, it may help you to make any decisions. I knew nothing about the risk of over vaccination when I lost my cocker two years ago. Every dog I've ever had was religiously vaccinated yearly and it was only one that made it to double figures, the rest were relatively young when they passed away from one form of cancer or another. It was when I lost my last cocker and researched auto immune disease that I became aware of the possible dangers of over vaccination.
I hope this helps you a little.