Those guys are too smart. When you start to write programs that are too big to understand as one lump, you start to learn to decompose your code and organize it in ways that help you understand it a little bit at a time. They never do that; they just keep the whole program in their head at one time. Tell them that a function should do one "simple" thing that makes sense as a unit, and they have no problem putting the whole program in that function.

Actually, I shouldn't say they are too smart, because they will continue to program like that even when it causes them problems....