For my healthy cats, I take them to the vet twice a year for an exam and, if necessary, vaccines. For my two cats with chronic health issues, I take them more often -- it usually winds up to be about 3-4 times a year. And, of course, if anyone needs to go in between that time, I do not hesitate to schedule an appointment. And, truth be told, it always seems as though someone needs to be seen for something -- whether it be a quick check-in, vaccines, or a more serious issue.
I work in a veterinary clinic and I have seen too many cases where health issues have arisen in just a few short months. Therefore, I am vigilant about having my kitties (and dogs) seen by their vet bi-annually. If something should come up, my hope is that it is caught early on and can be treated before becoming a more serious concern.
So, Emory and Delaney get a check up twice a year. And, if they need vaccines, I do take them in (though I do not necessarily vaccinate on a yearly basis). And, Cassidy and Finnegan go in more frequently. Cass has IBD and dental issues and Finn has allergies and dental issues -- if I were to take them in less often, things could potentially get out of hand.
So, what I do works for us. But, unless extenuating circumstances are present, my professional opinion is that pets should be seen yearly or bi-annually. Of course, it is a matter of what works for each individual, but that is where I fall opinion-wise. And, I always recommend having an open and honest dialogue with your vet. What works for one does not always work for all -- having a professional help guide you is key. And, it helps maintain a positive relationship between pet owner and vet.