How should an administrator support this request?

Process Builder triggers actions based on field changes but cannot calculate or store running daily stage averages on opportunity records.

Formula fields can reference current field values but cannot track historical stage duration across multiple stage transitions over time.

The Opportunity Stage Duration report is a built-in Salesforce report that tracks the number of days an opportunity has remained in each stage, providing direct visibility into stage progression and bottlenecks without custom configuration.

Reporting snapshots capture point-in-time data on a schedule but require custom setup and are not the standard mechanism for analyzing opportunity stage duration.