I guess it can't hurt to see a doctor once a year. I don't bother myself as long as I feel all right.
The way I see it, your body has a mean time to failure built in. The old ticker is going to give out at some point, and the best you can do is to baby it along: treat it well - get some exercise every day; don't eat too much fat, etc. If you do that you can probably get a few more years out of it. Same thing for the rest of your bag of bones. But if you drew a poor set of genes in the lottery of life, the old ticker will give out early and you can't do more than get those few extra years while still dying young. I think it was James Fixx, a fitness guru, who died of a heart attack at some ridiculously early age - early forties I think. His father also died early of a heart attack, and despite Fixx's exemplary regimen of diet and exercise, he went too. I think I read that the autopsy found a lot of fat had collected around his heart. The poor guy didn't have a chance. I try to get in a walk every day, and try to discipline myself enough to stay away from too much or too wrong food. I'm pushing 70, and feel pretty good except when I am too lazy to get a walk in for a few days, or eat too much junky food. In other words, I know exactly what is wrong with me when I don't feel well; I know just how to cure it. If I don't, it is because I have the usual bad habits and am too lazy to work to overcome them. And I think it is their bad habits that kill people before their time is up, not that they did not see a doctor every year. My time isn't up yet, and I can be healthy with regular exercise and sane eating; but one of these days my time will be up, and I will have a heart attack, or a stroke, or get cancer. And I will get those nasty things despite anything I, or a doctor, can do. If Fred was overweight and under-exercised, that killed him before his time was up; if he got regular exercise and ate intelligently, then his careful stewardship of his body allowed him a few years past when his time was up.
