I see where they're going now that it's pointed out. The X pattern defines a single point of control where the lines cross, while the 'diamond' pattern creates

I see where they're going now that it's pointed out. The X pattern defines a single point of control where the lines cross, while the 'diamond' pattern creates (roughly) four outer lines of contact and thus for a complex terrain beneath allows for better control in the location on top of that uneven field.