I guess a more relatable way of conveying this is that you can have the recipe from a michelin star chef, but you're still not going to get anywhere close to michelin star quality.
oh and post holes, some are easy and some you hit mystery chunks of concrete(!?). It was like archaeological expedition trying to get deep enough holes in the ground.
For quite a while, he hated having to test on real hardware because all sorts of failure modes that he couldn't predict: belts stretching, mechanisms hitting each other or not lining up properly and losing position, etc. kept happening and interfering with his nice "this will only take 15 minutes to test" estimates, making it an all-afternoon affair.
OTOH, it was that unpredictability and having to deal with weird stuff that I liked about programming embedded systems.