I think it all depends on the doctor and the hospital. In this country it is a lottery and you never really know what the hell you are getting. I know some people working in the health system here, most of them are very good having trained abroad and still try to do the right thing. An example is when my FIL was in hospital earlier this year and a friend of mine who works at that hospital, specialising in  pharmacology, came to check on the old man. He checked the medication and told us one of the items was not needed, by sheer coincidence it happened to be one of the more expensive items. Fil is ok now even though he never took that particular medication. However for every good, honest person in the health system there are many more who simply do not know what they are doing, at worst or at best, the medically proficient doctor who sees nothing wrong with racking up the cost for medicines whether they are needed or not.. As I said a lottery, you can never be sure whether the person who is diagnosing you is a doctor or a witch doctor. One small personal experience was when I went for the last medical in order to get my residents permit. The results showed my hearing to be fine, despite my right ear is almost completely useless; the urine test results were fine but I was never asked for a urine sample; and my eyesight was 100% despite the doctor being able to see the glasses I always wear. In this country money is king and when you mix that with a good dose of incompetence, laziness and good old fashioned not giving a f**k you wind up with what we all see here. Having said that I have nothing but praise for the dentist I have been to on two occasions, very professional, very cheap when compared to my home country and I have never had a problem withe work carried out.

Annual health checks can be a good thing : detecting a cancer early, before it grows beyond hope. There are other things like diabetes, etc. that health check can catch. However, with the number of undiagnosed diabetes and cancer in China, I think something went wrong somewhere.

For cancers early detection, annual checks is an expensive overkill. A smarter (and less expensive) way is to do specific checks only on the people likely to be at risk. For example, breast checks in women after 30 years old. The examination is quick, because it's focused on one thing, and it allows to find a cancer when it's still mostly harmless. Same thing for prostate cancer, respiratory problems (ie. you would check on miners and smockers ,often, but not very often on non-smocking farmers).

I have found it common in now 3 countries including China that when you go to the local GP you need to know what you want. 

ie; If you have and annual health check and you don't ask for anything specific such as a diabetic check or a heart echo check they won't put it on the list of things to be checked.

The patient needs to be pro active

or a hypochondriac