I don't understand the first example. The author talks about an unplanned node, literally called it "I was unplanned", and then says "if you have planned ahead"

I don't understand the first example. The author talks about an unplanned node, literally called it "I was unplanned", and then says "if you have planned ahead"... How can I plan agead for something unplanned, in the context of a diagram? Do I leave sufficient white space around all nodes? Also, the suggested improvement makes it look like "something" and "I was unplanned" are somehow related, or use the same channel/mechanism to interact with "engine"