I can lay out a solid circuit for most jobs now without breaking a sweat. But the high-speed, high-performance ones throw problems at me I didn't know existed, and the board misbehaves in ways the textbooks never mentioned. I'm good enough to know exactly how far I still have to go.
More people experience this than they realize.
You can design most circuits, but the complex high-performance ones still defeat you.
If this sounds familiar, the Library can help you find the bigger picture.