Basing medical care and treatment on the scientific evidence should be the norm, but frequently it is not. Doctors may treat based on how they have always done it, or how other doctors do it (i.e. best practices), but there is a movement now to reorient medicine to follow the best scientific guidelines.

https://en.wikipedia.org/wiki/Evidence-based_medicine

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3789163/

https://en.wikipedia.org/wiki/N_ray

https://www.palain.com/?page_id=360