["Strategic Management Journal, Volume 47, Issue 5, Page 1433-1466, May 2026. ", "\nAbstract\n\nResearch Summary\nCo‐using tasks—using the same task to produce more than one product—promises economies of scope. However, task co‐use also ties products together, changing a firm's task network by introducing cross‐product interdependencies. In light of these interdependencies, we identify an unrecognized downside of task co‐use for product reliability: Cross‐product interdependencies complicate task design and increase the risk of malfunctions. Hence, task co‐use may carry a reliability penalty. Second, we propose that the reliability penalty of task co‐use may shrink with experience as cross‐product interdependencies allow for cross‐improvements and therefore potentially higher improvement rates of task co‐using products. We study the US automotive industry and find our predictions supported, indicating that task co‐use is a critical design parameter with important consequences for reliability and product improvement.\n\n\nManagerial Summary\nUsing the same tasks to produce multiple products can help firms lower costs and achieve economies of scope. However, this practice also links products more tightly together, creating interdependencies across product lines. These interdependencies can make tasks harder to design and manage, increasing the likelihood of errors or malfunctions. As a result, task co‐use may reduce product reliability—an important but often overlooked drawback. At the same time, co‐used tasks can enable portfolio‐wide improvements— improvements across products. As firms gain experience, problems identified in one product can lead to improvements that benefit others using the same tasks. Over time, these cross‐improvements accelerate product improvement for task co‐using products and can reduce the initial reliability disadvantage. Evidence from the U.S. automotive industry supports these arguments. The findings show that task co‐use is a key design decision that involves meaningful trade‐offs between cost savings, reliability, and improvement. For managers, this highlights the importance of carefully evaluating when and how tasks should be co‐used across products, as these choices have lasting implications for product quality and improvement.\n\n"]