Does Stern only operate with a single shift per day, or do they also have the capability and manpower to run double or triple shifts? Multiple shifts could put a serious dent into the production target, while keeping labor costs controlled.
In a contract manufacturing scenario, I doubt either party (buyer or manufacturer) would be willing to eat overtime costs. Normal OT (time & a half) chews up profits quickly. Holiday OT (double time) is practically unthinkable outside of hard deadlines with liquidated damages attached.
Also, what is Stern's normal practice for physical inventories? Even if they have a perpetual inventory system in place, their audit &/or lender requirements may also dictate that a year-end physical inventory take place.
For manufacturing companies with a fiscal and calendar year in sync (i.e., both ending on 12/31), many choose to conduct physical inventories in December because the manufacturing schedule during the Christmas holidays is often slow anyway, and physical inventories require that manufacturing shut down for a period of time to ensure accurate item counts for all Stock Keeping Units (SKUs). Obviously, if they have to halt manufacturing for a period of time to complete a physical inventory, that would lower the amount of finished goods that could be produced in the period.