In the scenario described, where an organisation suffers from poor test estimations despite many practices being in place, the process area that requires attention is Test Planning. Specifically, SG 3 (Establish Test Estimates) focuses on developing well-founded estimates for testing effort and cost. This includes creating a top-level work breakdown structure, defining the test lifecycle, and determining estimates for the test effort and costs associated with different test activities. By addressing these practices, the organisation can improve its ability to generate accurate test estimations, leading to better project planning and resource allocation.