Most patients want to go to the doctor who has special expertise in handling their particular problem. They will spend a lot of time and energy tracking down the "biggest name in the feild" - and then leave everything upto the doctor. This can often be a short-sighted approach, because specialists are biased, and it's important to be aware of this bias.
While it's true that an expert has a lot of experience in dealing with a particular problem, this extensive experience also introduces all sorts of bias in the way he handles this particular problem. There are many reasons for this.
Because he is used to seeing complex cases which have been referred to him , he often cannot deal with simple bread and butter problems ! He also sees life through a distorted lens, and may not be able to see the big picture. Because he cannot afford to make mistakes, he often overtests and overtreats. He often asks for esoteric and expensive ( and painful) tests, to differentiate himself from the other ordinary doctors. He also usually bad-mouths alternative options of dealing with the problem - after all, this is his competition ! He is reluctant to refer cases which he canot handle, because this would damage his aura of omnipotence and omniscience.
Often, in the pursuit of narrow goals, he loses objectivitity; and is more interested in doing research rather than treating patients. Many experts are so used to seeing only sick patients, that they often cannot recognise a normal variant !
An excellent example of how many experts mismanage patients is the patient who has had recurrent pregnancy losses. These are "heart-sink" patients, who are often at their wit's end. Having suffered so many miscarriages, and visited many experts, they are emotionally very vulnerable and are eager to grasp at straws. The specialist - since he is a specialist and the "court of last resort" then needs to perform "new" tests - which no one else has done, in which he is the specialist. Often, these are tests which the specialist has invented himself, which means he has a lot of energy invested in them. A good example are the extensive battery of "immune testing" performed for patients with RPL.
Now, it's a mathematical certainty ( and simple common-sense ) that the more the tests you perform, the higher the likelihood that at least one will be abnormal ! If you perform a panel of over 20 tests for any woman, at least one ( or even more) are going to be "abnormal". This condition, when the result of the test is abnormal , but the patient is normal, is called a "false positive test". Unfortunately, because specialists are biased and often have blinkers on, they treat all abnormalities as true positives. He is very pleased that he has finally "diagnosed" the elusive problem - and then goes about treating it. Actually, the abnormal test result is just a red herring which has little to do with the illness - but the patient is also equally pleased that this new expert has cleverly found the problem which all the earlier experts has "missed".
The biggest problem is that many patients with recurrent pregnancy losses will then go on to have a healthy baby in the next pregnancy, even if they don't take any treatment at all. Now if a patient takes "immune therapy" and then has a live birth, she is happy to give all the credit to the expert - and the expert is happy to take the credit even though it is undeserved ! In fact, many patients go on to have healthy babies inspite of the treatment, and not because of it !
The patients who fail get discouraged and leave the specialist . They continue their quest for another expert with a new bag of tricks, as a result of which the specialist naturally gets the impression that his treatment is spectacularly successful, because only his success stories come back to him - the failures drop out ! This creates a vicious cycle, in which he goes about propagating his treatment at conferences - until other doctors try to repeat his successes - and fail miserably. It's only then that we realise the Emperor has no clothes !
All this causes a lot of harm. Not only is a lot of time, money and energy wasted on these unproven tests, they also cause a lot of emotional trauma. The purpose of a test should be to reassure a patient, but abnormal results create a lot of anxiety and distress in patients, which make a bad situation even worse.