You'll find that marginal treatments when there is brood will sometimes not appear that effective even though they are getting rid of some mites. You'll also see why treating when there is not brood in the hive is MUCH more effective.
Maybe this wasn't addressed to me but I'll add a comment to it. I got 5 of the 8 hives I have last spring from an old fella that has since pasted on. The other 3 were swarm captures I suspect came from the same bee yard. Sam ( the ole' fella ) never treated for anything and after he was gone I checked his hives and all his equipment that he had stored away on the property. It was a mess. Moths were killing his hives left and right - he had 40+ hives - I would say 20 were killed off with in 2 mons. due to a massive moth infestation. There were moths flying everywhere in the storage areas - you could lift the top covers on any hives and they would just go everywhere.
A friend and I saved about 15 hives - we barely saved them after changing out frames that were infested with moths with just frozen frames. Some of the ones we saved were pulled from sure death had we not got involved. Some hives are still sitting where they were - the frames complete encased in moth webs. Sam just didn't have the time - the information - the will or whatever to take care of the hives anymore. He had them for about 8 yrs. when I got them.
Having said that and not knowing the history of of mites at his place I felt I needed to treat these hives at least once with something strong to kill off any on coming mite problems. I don't have a problem now and these hives are doing good from all I can tell. Last yr. I would not have taken a bet that any of them would make it past Aug. - we're talking a moth breeding facility...
As I posted before - I won't treat for something I don't have. Hopefully I won't need to use anymore mite begone.