One of the most neglected disciplines in many churches and ministry organizations is that of doing exit interviews when staff leave. In fact, in some cases, I believe that some leaders don't want to do candid exit interviews because they know they have a problem with retaining staff and frankly don't want to address it. Yet, had they conducted candid and confidential exit interviews they would know how to address the issue.
What can exit interviews tell you? First, they may tell you why a staff member is actually leaving. Let's be honest. In many cases in ministry settings staff don't reveal the actual reason they are leaving out of concern for the organization or because they are under pressure not to rock the boat. If there is an underlying reason for their exit related to the culture of the ministry it is a good thing for you to know this.
Second, if there is a dysfunctional staff situation, and you see trends (see my blog, When the bodies pile up), the exit interviews give you information that can be used to address whatever dysfunction exists. That is, if you truly desire to do so. In some cases, in spite of problematic trends, leaders simply ignore the problem not wanting to deal with it. However, common stories when people leave do give you some helpful data to address underlying issues.
You may also discover that your hiring processes are not robust enough if there is a trend of people who don't fit. Poor hiring practices lead to a higher attrition rate which is unfortunate for the staff member as well as the organization.
One thing to remember is that people may vent on their way out so their own experience can be colored by their issues. One problematic exit does not make a trend. Over time, however, if there are consistent themes around any issue of staff health or culture the exit interviews give you an opportunity to address it.
As the leader of an organization, I take the feedback from staff who leave seriously. It gives us an opportunity to improve our culture and practices. I am given regular feedback from our personnel folks on trends that they pick up. Don't neglect your exit interviews. They are crucial to a healthy organization.