It's more like you have a massively parallel program that you compile ten million times, but only five million complete the process usable afterwards and of tho

It's more like you have a massively parallel program that you compile ten million times, but only five million complete the process usable afterwards and of those five million, they may or may not have all the parts of the program you intended in the binary. And you have very little insight into it while the compilation takes place. And you have to check/debug those 10 million compiler passes at various stages, and each design change may require developing a new debugger or disassembler from scratch to plug into the compiler at each stage of compilation. What I'm saying is that CPU designs aren't programs, because you can generally trust the compiler to be infallible (and compiler bugs are there, but they're rare). In a CPU process you have to consider the physical impact of the design on manufacturing, what yields you get, how the product is binned, and so on. There are feedback loops between the packaging, testing, and design teams to alter the silicon before production ramps up to go to market. There are tons of moving parts to the actual design process itself, let alone what is being designed.