That strongly depends on who you are. They really are a custom design house, that's where they make the money. Standard products are there only to keep the fab full.
At Infineon Fiber Optics we sometimes felt besieged by their field engineers. No wonder if you can sell modded parts to a company that has 300 people working alone in the pilot preproduction line.
And for Verigy they made and delivered special mixed signal chips for the 93000 wafer tester. I heard nobody complaining about them.