Even with preparation, not all things go as planned. Your interview may be running behind schedule, or perhaps the interviewee reveals relevant information that pushes you to ask a different set of questions. Having more than one plan for how you can approach your interview can help you remain on track and in control of the process. It helps to have more than one set of questions to go to. Maybe plan to ask certain questions if your candidate has impressive qualities on their resume like having a master's degree or serving in the US Armed Forces.