At the moment its useful only in depopulated shards, wherein the still-higher number of Horde won’t equate automatically to a corpse run marathon, which still ends up around 90% decrease to experience generation over time (now 87%). Once its worth more than that minor mitigation to a problem so great it still keeps you out of Warmode, the bonus is no longer available. It’s constantly rechecked based on available population balance/distribution across shards.