That seems unbelievable. Do the doctors _never_ find a heart attack, or get a patient treated for high blood preassure or skin cancer?
Of course not, it's just rare to find problems without symptoms. And going for a check up is not without risks. Sometimes doctors produce false positives. Sometimes you catch a bug in the doctor's office that you would not otherwise have gotten. Going to the doctor can be stressful. All of these things are small effects, and they all generally cancel each other out so that the net effect of going for a routine physical is a no-op.
There is no evidence that routine checkups lead to better outcomes.
http://www.health.harvard.edu/blog/a-checkup-for-the-checkup...
"But what are the true benefits of this practice? Careful reviews of several large studies have shown that these annual visits don’t make any difference in health outcomes. In other words, being seen by your doctor once a year won’t necessarily keep you from getting sick, or even help you live longer."