Sorry, I made a little typo at the end of that post that makes it read wrong. Where I said
shouldn't be any live active mites by now.
I meant
adult mites.
I'll assume the treatment is ivermectin as that's a very popular and effective treatment. It should be two drops directly to the skin (not the feathers) at the back of the neck. It works by spreading throughout the body so any feeding mites get a dose and die, leaving just the eggs. The second dose at 14 days is timed to kill off the mites from those remaining eggs before they are mature enough to lay their own eggs. So the chain gets broken and all the mites are gone.
Any variation from this will reduce the effectiveness of the treatment making it useless.
I would have expected after the first dose there would hardly be any activity at all as the feeding population would effectively be reduced to zero.