For many years, I have wondered at how useful an Exit Interview truly is when it comes to allowing corporations to find out why people are leaving, and address those issues. The Exit Interview is mostly an HR administrative closure process.
Several observable facts have convinced me that exit interviews are fundamentally limiting in what they can achieve:

1. Departing employees rarely tell the full story about why they are leaving during an exit interview. They usually do not want to burn any bridges in case they want to come back at some point in the future.
2. The Exit Interview takes place on the last day of employment. This is too late (for example) to address any issues that may have caused the employee to want to leave in the first place. The interview can only be a post-mortem, not a remedial exercise.
3. Senior leaders are rarely involved in Exit Interviews. The interview is usually conducted by a middle-ranking person filling a full-time or part-time HR role. Any messages that the departing employee might want to provide about fundamental corporate dysfunctionalities are going to be filtered (and possibly distorted or lost), which reduces the chance that senior leaders will need what they need to hear.

My conclusion is that Exit Interviews are not fulfilling their potential for addressing issues that cause employees to decide to leave. I would recommend the following changes:

1. A remediation interview should be arranged with any employee who has resigned within 24 hours of that resignation being tendered (assuming that the corporation does want the employee to stay, which may not always be true...). The purpose of this interview is to understand why the employee wants to leave, and to assess what actions (if any) are possible to persuade the employee to stay. The employee's normal management chain must not be involved in this interview, since that may prevent the employee from speaking freely.

2. Any departing employee should be offered a chance to speak to a senior leader during the period before his/her departure, in order to explain to that senior leader why they decided to leave. It should be made clear to that employee that this interview will not have any influence on whether the corporation would want to re-hire the employee.

3. The last-day Exit Interview should be a purely administrative departure management process.