A heat exchanger can deliver colder coolant without necessarily delivering a better cooling system. That outcome becomes increasingly important as AI infrastructure pushes thermal management beyond the operating assumptions of conventional data halls. Engineers now face a design environment in which coolant temperatures, heat loads, hydraulic conditions, and heat rejection strategies must work together across an increasingly interconnected thermal chain. A heat exchanger that achieves an exceptionally tight approach can improve thermal performance, but its overall value depends on the additional heat transfer surface, hydraulic resistance, pumping requirements, equipment dimensions, and control conditions associated with the selected design. The resulting system may transfer heat effectively at its design point while becoming less economical and less adaptable under changing operating conditions.