It's something they'll run a batch for occasionally, but thats normal. Fabs are not like one long conveyor belt where a wafer goes in at the front, passes throu

It's something they'll run a batch for occasionally, but thats normal. Fabs are not like one long conveyor belt where a wafer goes in at the front, passes through a long sequence of machines and falls out finished at the end. They work in batches, and machines need reconfiguring for the next task all the time (if a chip needs 20 layers, they don't have every machine 20 times), so mixing different products and having products is normal. Low-volume products are going to be more expensive of course due to per-batch setup tasks being spread over fewer wafers. In general scheduling of machine time and transportation of FOUPs (transport boxes for a number of wafers, the basic unit of processing) is a big topic in the industry, optimizing machine usage while keeping the number of unfinished wafers "in flight" and the overall cycle time low. It takes weeks for a wafer to flow through the fab.