Rarely are full designs respun. That’s a huge waste of NRE cost. Lithography masks are millions of dollars.

Devices are characterized and techniques are explored on mpw designs. Multiple Pattern Wafer. Many customers design a small test die, and they are stitched together to make a single wafer and then you’ll get a few dies for evaluation. This way the cost is shared between many customers and experiments.

If even one mask (out of dozens) needs rework after a full design is getting fabbed, its considered a big error.