As the complexity of today's products increases, single projects, single departments or even single companies can no longer develop total products, resulting in concurrent and distributed development. To manage the resulting organizational complexity, projects need a lifecycle that explicitly reflects the concurrent and distributed nature of the project context. This paper addresses the essence of lifecycle modeling, with emphasis on defect detection. An adequately modeled lifecycle allows the localization and recognition of defect-sensitive areas in complex product development. A case study involving real-life development projects indicates that transitions between constituent sub-projects are in particular defect-sensitive. A second case study shows that by a defect detection-driven construction of a project-specific lifecycle, fewer residual defects can be expected.