By default, when the Maximum Discovery Run Time limit is reached, the Full Discovery process will stop after it has finished processing the current site collection. For farms with deeply nested sites, however, ControlPoint Application Administrators may want to specify a location within the site collection at which Discovery will stop by changing the Value of the ControlPoint Configuration Setting Depth at Which to Stop Discovery When Time Restriction is Reached.
The number you enter represents the depth below the site collection (which is represented by 1, the default value) within the site being processed where you want Full Discovery to resume the next time it runs.
When the Depth at Which to Stop Discovery When Time Restriction is Reached limit is reached, Discovery will finish processing the current site and its immediate children. It will stop when it reaches the specified level within the next site in the site collection.