This method depends on reviewing lessons learned from previous projects. Its use must be approached with some care, however.
Project close-out reports are the usual documentary source of reviews of lessons learned from improper management of unanticipated risks or other failures during project execution. However, ISO standards setting out quality standards to be maintained at all stages of project execution may neither have been followed nor existed for many projects executed before the 1990s, not to mention the broad principles that Project Management Professionals are expected to be following today. The documentary review method works best for companies that have performed this type of project before many times, and maintained their own database of lessons learned. Its inherent attractiveness is cost, which is effectively zero.