When you have a large diagram to create in Visio, and it contains many hundreds of nodes, some limited automation is available and useful.
So it was that the Gorse Fox took the spreadsheet that he had been working on for a few days and connected it to the various pages of the diagram and created suitable data links. This allowed all of the nodes to be generated and populated with the correct information, at a stroke. Then GF just had to worry about layout (there is an automatic layout function - but GF wanted to determine this himself) and the connections between the nodes. This latter aspect would be great to automate but the very purpose of the exercise (in this case) was to work out and document the connections.