That illustrates it perfectly. The monuments follow the road. In your example, where the land is hilly, the route must follow the terrain and so straight lines will not be apparent. Elsewhere, straight routes can be seen for very many miles. Textbook version is that Roman surveyors were the only people capable of surveying straight lines over long distances and did so through virgin forest and featureles moors. Yet I can show straight tracks in eastern England that have long barrows, henges, round barrows and hillforts alongside. All were in place and served by the trackways long before the Romans took them over. Now, of course, we have done the same and turned them into stagecoach routes and then A class trunk roads.