How are wings even that descriptively useful?
I personally find it much more descriptive to include the number 5 in my enneagram than 8 or 1 (I'm a 9). I just think of the wings as a way to sneak in a 2nd-best type. If you have only a finite number (two) slots to include information, why not include as much as possible?
Also, the lines of integration make no sense.