During a construction project, the production control system allows the creation of conditions to manage operations. The Last Planner System is a production control system whose use has been related to superior project performance. We suggest that there is an opportunity to improve the Last Planner System application in the patterns of conversation variability along its subprocesses from a Language Action Perspective. These patterns are called Bullwhip Effect of Conversations, because they resemble the concept of propagation of variability in the supply chain. We update previous research about Instability of Conversations, adding new data, evaluations and interpretations. This paper is based on five mining and road construction projects. Our research analyses variability propagation and distortion of conversations along the Last Planner System subprocesses, and their relationship with the Percentage Plan Complete Index. The findings suggest that the Bullwhip Effect of Conversations exists. It impacts the production control reliability. Also we conclude that it represents the coordination variation throughout the production control subprocesses. This concept seems useful to improve management processes; further research is still required.