There was a great TR from IBM describing memory system design for one of their PowerPC chips. Summary: Do your board layout, follow all these rules [a big list], then plan to spend six months in a lab twiddling transmission line parameters and re-doing layout until you're sure it works . . .
Analog is a black art.
Long story short was that spansion changed from gold to copper feeder wires inside their memory chip and was in every so many chips causing bit flip problems.
Our end product is in the automotive space averaging 300,000 units per year. It's a non safety related component.
Hiding complexity behind abstractions is what allows us to build complex things.
For a small example, Look at the simplest SR latch circuit... It's metastable because it feedsback into itself.