Sarah Chen manages 12 assembly lines and 2,000 machines. Before her 10 AM production review, she needs one answer: Which lines need attention this week? Simple question. Painful journey. She starts in the IoT dashboard. Line 4’s motor temperature is running 12°C above baseline — has been for three days. Calibration drift or bearing failure? The dashboard shows signals, not causes. So she pivots to the ERP system for maintenance history. Machine 42 had a bearing replaced eight months ago. Warranty says 12 months, but the operating hours log — buried in a separate historian database — shows it’s been running at 130% rated capacity since January. That context exists nowhere in the IoT dashboard. She pulls 30-day OEE trends. Line 4’s availability dropped from 94% to 87%. Line 9’s throughput also dipped 6%. Related? They share a coolant loop, but that relationship isn’t modeled in any system. She checks defect rates. Line 4’s scrap jumped 2.3% last Tuesday. Line 9 shows nothing — yet. Is the coolant theory wrong, or is Line 9 just lagging? She emails three supervisors. By 11:15 AM, she finally has a confident answer. …