That’s what happens when a planning tool works at a weekly level and stops short of the day-to-day floor workflows. ERP modules, legacy schedulers, and custom spreadsheets might get you close, but they leave the last mile to manual input. So the plan changes daily, the floor runs off a handwritten list, and the one person holding it together is your only backup.
A schedule that isn’t buildable isn’t a plan. It’s a guess, and you pay for it in throughput, inventory, and on-time delivery every day it runs.