I can understand that if you have lots of hives.
I have one colony that was still dropping considerable mites despite vaping seven times. I put Amitraz in and now have forgotten about them till spring.
I have two colonies that are dropping mites again six weeks after the first round of vaping finished (Lots dropped with the first two and very few with the third so I presumed it was successful).
I can see the attraction of Amitaz but I don't like the idea of what it is
Use your autumn OAV as a 'knock back' to get healthy winter bees. Save the 'knock down' for winter OAV when brood is minimal.