believe one of the reasons physicians are slow to change their treatment methodology is because of liability.  while new research has shown that maybe certain tests may not be necessary due to prior studies, each patient is an individual and the "norm" may not apply to them.  As such, they maybe liable for malpractice if a test is not given and the patient become worse.  change may come but it will be slow until a new generation of doctors schooled on the new technologies and research, but those doctors who were schooled under the older principles maybe reluctant to change as research shows tendencies and they are not absolute and cannot be applied to every case with the same result.