One exception that comes to mind about a particular speciality of a doctor, ant thier ability to act and decide is in the field of psychiatry.
Comparatively speaking, Psychiatry is a rather soft science. Most disorders and illnesses in the field of psychiatry are open to conceptual definitions. Mental health illnesses are assessed and diagnosed by psychiatrists, and often other doctors according mainly to thier own discretion and opinion based solely on the subjective aspect of thier exam of such a patient. Screenings and questions are asked, yet no diagnosis regarding mental illness can ever be confirmed. The Diagnostics and Statistical Manual or DSM, is the Psychiatrist's bible, as it is used as a guide and reference to mental illness.
The specialty of psychiatry is probably why there are so many psychotropic medications aviailable for those patients with questionable if not actual mental disorders in order for treatment options to exist for such patients. The makers of such drugs have been accused of creating certain mental dysfunctions in order to expand the use of their promoted psychotropic medication, which a process known as disease mongering. This, of course is viewed as inappropriate. The Psychiatry specialty does receive the most funding out of all doctor specialties from the pharmaceutical industry.
It's a guessing game with psychiatry and mental illness, and a potentially dangerous one at that, even if the prescriber's intentions are righteous, and believe the prescription given to such patients for mental illness suspected is reasonable and necssary.
However, what statistically has been proven is that psychotropic drugs, according to the patients who have or are treated with these drugs, have stated frequently that the drugs they have taken over time have benefited the disorder they believe they have had and have, according to the patients surveyed, as well as improving thier well-being. But it raises the question: Was it the medication- or the time that passed that improved these patients? Does the life stressor or issue correct itself with the person on such a drug, or was it in fact the drug? One can only speculate.