I can design a robot that works, one that does what it's supposed to on a good day. But the ones that have to hold up in the real world, through heat and dust and years of abuse, still beat me. Getting from working to actually robust is a wall I keep hitting.
More people experience this than they realize.
You can design working robots but the complex, real-world-robust ones still defeat you.
If this sounds familiar, the Library can help you find the bigger picture.