it's not really that randoming for land is uncommon, it's just that there is limited opportunity for it. Part of the issue is that, over the course of the age, the top kds wind up with more of what 'inflates' nw than other kds do -- more science, more gc, more wiz. The flipside to that is that top kds can manipulate NW to extend the whoring range.
But since most kds don't grow very much, you tend to wind up with very limited target options.