Ordering an extra test or an extra drug is mostly a doctor covering themselves from potential lawsuit.
People are tremendously impacted, for good or ill, when prescribed pain medications, ADHD medications, anti-depressants, etc. Many of these people are harmed. Many of the doctors who caused them harm simply do not care.
Then before you know it, you have to take a pill to take a pill. Then down the road, you have to take a pill to take a pill to take a pill.
I'm no medical Calvinist either, but I am not sure that polypharmacy should be the end goal if it can be avoided.
Doctors may care about treating patients, but hospitals only care about one thing -- money. Pressuring doctors into pursuing unnecessary treatments are one of many ways hospitals try to increase revenue.
However, when learning for exam, it is cheating, because exams define minimum set of stuff that you should have in memory at that point.