I've decided to experiment a bit with the blue and yellow linked nodes to see if, after deleting a single node that is connected to several blue or yellow linked nodes, whether or not they would stick around, and if so, what is the pattern for these unconnected nodes.
I've found that every even-placed node that was connected to the formerly deleted node will remain. Although it is impossible nowadays to save the system with these nodes in place, it does get annoying deleting multiples of these if you made a mistake with the placement of, say, a goal node connected to multiple nodes, and you the goal node, leaving behind these unconnected nodes.
I've tested this with 6 or more nodes connected to a single node, but I will see if it pops up at lower connected numbers of nodes.
Edit: It occurs with 2 connected nodes as the minimum. For an example, delete a goal node with 2 blue or 2 yellow connected nodes, one blue unconnected node will remain. 10 nodes, 5 remain.
Let's say that for this next example, yellow nodes are the 1st, 3rd, 5th, and 7th node placed that is connected to the goal node, and blue nodes are the 2nd, 4th, 6th, and 8th node placed that are also connected to the goal node. Deleting the goal node will remove ALL of the yellow nodes, but will keep the blue nodes behind.