The idea here is 'stay out of dirty air better'. It isn't a real gain for the downwind turbines, just less of a loss. This concept has long been known to sailor

The idea here is 'stay out of dirty air better'. It isn't a real gain for the downwind turbines, just less of a loss. This concept has long been known to sailors. And I presume that sailing in convoys took this effect of dirty air well into account.