I have discovered that, in mythic plus, if you use Primal Rage (hunter pet heroism), then dismiss and re-summon your pet (or die and release), that the CD will have reset. Obviously you can’t use this with the exhaustion debuff active, but if the timer expires you can effectively hero every remaining pull so long as you “patch up” between them.
This doesn’t seem to happen outside of instances, that I can reproduce anyways.
Unsure if this is intentional.