To ensure the quality of integrated circuits, semiconductor manufacturing companies need to respect Time Constraints (TC). Time constraints are critical times not to exceed between two operations or steps in a product route. More broadly, a set of consecutive steps under at least one TC is called Time Constraint Tunnel (TCT). These quality requirements, added to other challenges in a High Mix/Medium Volume (HM/MV) fab (e.g. long cycle times, re-entrant flows and heterogeneous complex machines) become stressful for operators regulating TCTs in real time. Moreover, understanding the effects of mid-term changes can be difficult to qualify and quantify given the high complexity in semiconductor manufacturing facilities (fabs). This paper focuses on the management of releasing lots in TCTs at the operational and tactical levels using a simulation-based approach.