Trial and error is a fundamental method of problem solving. It is characterized by repeated, varied attempts which are continued until success or failure is concluded.
Medical schools teach trial and error methodologies of beginning drug treatments with the smallest dosage first. Testing follows to determine how the doses work. If results are not successful then increased doses over time are prescribed, tested, and determined if effective.
If no efficacy (success) is evident, medical students are taught to then try other medications.