Based on self-efficacy, team potency, group dynamics, and normative decision theories, we argue in this study that certain project team characteristics, namely, team management skills and team stability, affect the project-planning mode and that planning mode is related to the speed of project completion and project disturbance. We summarize our arguments under five hypotheses, one of which postulates a mediation effect between the two project outcomes. The analysis of 410 projects from the UAE reveals that adopting a more deliberate mode in planning projects is more likely to succeed, and consequently, it demonstrates the importance of normative decision theory as a theoretical lens in the context of planning projects. Our findings offer some implications for both academia, which we discussed in relation to theoretical lenses and contextual variables employed in this study, and practice, which we discussed in relation to team stability and team building and development.