In other fields of medicine, this may not be the case, but in the mental health world, evidence based practice is a relatively new development.
“Evidence-based practice” means we conduct our clinical practice based on evidence that we’ve acquired from clinical research. Similar to drug research, your doctor will usually prescribe medications that’ve been tested thoroughly through many trials, and have been proven to benefit your health condition. Once upon a time, your therapy could’ve been based on Dr. Ego’s clinical expertise, big name or great insights, but thankfully these days such practices are slowly becoming a nightmare of the past (although, drug companies still invest on armies of Dr. Egos “aka opinion leaders” to influence your local doctor’s prescription practices).
However, evidence-based practice is a fairly recent development in the field of mental health, and especially in the field of psychotherapy. The rise of behavioral therapy in the 60s, partly as a reaction to the psychoanalytic status quo, and later its marriage with cognitive therapy, have given us a remarkable new tradition of true evidence-based psychotherapeutic practice.