On the iPad Pro Applications has the form 5 × 4 in landscape orientation and 4 × 5 in portrait. For comparison, in the iPhone 6 Plus is using a grid of 6 × 4 and 4 × 6, respectively. This ratio is meaningless. Why a small iPhone screen can fit twice as many applications than on a huge screen iPad Pro?
The size of the new iPad Apple changed encourages grid arrangement of icons not only to display their large number, but also to display other types of information. For example, the iOS 10 widget and new iOS 10 Home Screen.