Previous research has found that that software inspection teams that use group support systems (GSS) are more effective and efficient in finding defects than inspection teams using the traditional paper logging method. In an earlier study, GSS-supported teams found forty percent more major defects and forty percent more defects per inspection hour. This paper extends previous research by examining the underlying factors that led to these improvements. This study found two major contributing factors: 1) greater attention focused on finding defects for both inspectors and moderators, and 2) greater adherence to target preparation rates over time. Both factors significantly improve inspections efficiency and effectiveness.