Zhao Yi decided to use a "process of elimination" first, to rule out incorrect methods. As long as the devised plan had no major flaws in its argumentation, he could directly design experiments for verification.
This was similar to selecting an answer.
For example, assume there are 100 possible answers, with 20 potentially correct and 80 definitely incorrect. Argumentation can eliminate most of the wrong options, and the purpose of the experiment is to identify the incorrect options among those "potentially correct."
After one round of experiments, there might only be 10 left that are "potentially correct."
Then, from these ten "potentially correct" options, he would find methods to design experiments, greatly increasing the chances of producing results.