Why do the big, complex landscapes still stump me?

You can design most landscapes. That is not nothing — most people cannot. But the large, complex ones stop you, and you are tempted to call this a gap in talent. It is not. It is a gap in exposure. You have simply not yet stood inside enough big projects to know how they work. A large landscape is not one impossible task. It is many ordinary tasks you can already do — a bed here, a path there, a drainage line, a sightline — connected in ways you have not practiced connecting. What overwhelms you is not the design. It is the number of decisions held at once. This will not be solved by reading more or waiting for confidence to arrive first. It is solved by taking one large project, working it badly at first, and finding the exact point where your current skill runs out. That point, once named, is no longer frightening. It is simply the next thing to learn.