And all 13 parts of that aircraft that was "designed" they cannot know whether or not that design was the best optimal design possible. It's just a best guess,

And all 13 parts of that aircraft that was "designed" they cannot know whether or not that design was the best optimal design possible. It's just a best guess, because they lack the ability to calculate the optimal configuration for that aspect of the aircraft, hence why they turned to "design" instead. That is for sure a lack of knowledge and is exactly what I'm referring to.