Some pet websites are owned by vets who use the sites and the anonymity of the net as a way to drive business their way. More than once I've come across articles that tell pet owners how important it is to have your dog vaccinated REGULARLY, undergo healthcare exams, etc - stuff which earns the vets a considerable amount of money. Much as preventive care could save you a lot of cash in case of an infection, the fees you pay the vet could add up to ridiculous amounts of money if the pet never does get sick. So, how often do you think one should take their pet to the vet. Once a year? Two years? Or never unless the pet gets sick?
Sadly, my answer is - never, unless our dog gets sick. My parents live in the countryside and no vet is to be found in the proximity, you need to travel a good 30 miles to find the nearest one. Thus, our German Shepherd never visited the vet until he got really old. At that point my parents invested a lot of money in his health, not because it was sick, but because they wanted to prolong his life. The meds were not cheap, but who cared, friendship is priceless and he got to live some more.
There's nothing wrong with that. Lots of people who live in the countryside actually learn to do some basics like neutering their pets which would save them from $50-$300 depending on where they live. From experience I know that a pet can stay more than three years without getting sick. So I agree, sometimes it's much better to wait until you see symptoms of sickness before seeing a vet. I think all that preventive stuff is a waste of money.
I've read that if your pet is young, then it is recommended to take him to the vet at least once a year. When he's older, take him twice a year in span of every six months. Moreover, it is a must that you bring him if an immediate signs of illness occurs. PS: This depends on your pet. This one that I put in here works well for mammals.
I try to take my cats to vet at least once a year from a basic check up. A variety of issues can come up the older the cats get just like humans. Obviously, expenses can dictate how often I can so I am not always able to do this. But this is right time frame.