Comment by pixl97
The point is until you start ripping the application apart you have no idea what the internal logic looks like.
When you look you can find terrors that will haunt you in the night where some ancient limit, say number of columns in a database end up holding multiple structures that are getting if/then'd later in the application.
I would completely and totally believe there is code just like that.
Why can’t you draw a flowchart/diagram of the logic?
Sure it may be so complex that a complete diagram would be dozens of feet across and tall on a real piece of paper.
But with apporpriate software tools that is not a limitation.