This is the configured pacing interval between unreliable, no-ack EIGRP packet transmissions, mainly governing how tightly-spaced Hello packets can be sent on this interface. Because Hellos ride the unreliable path, this pacing interacts with the Hello interval setting, and a pacing value too large relative to the configured Hello timer can cause Hellos to be delayed or dropped under load. On a link where Hello interval is set to 5 seconds, a pacing value creeping up toward multiple seconds would mean the interface can barely get one Hello out per interval, risking missed neighbor keepalives.