I can make my own corner run smooth; my part hums. But when I try to see the whole operation at once and fix where it all snags together, I lose it. I speed up one station and the bottleneck just moves down the line, and I can't hold the whole picture in my head long enough to untangle it.
More people experience this than they realize.
You can improve your own area, but optimizing across the whole operation still eludes you.
If this sounds familiar, the Library can help you find the bigger picture.