My vet told me that 80-90% of dogs diagnosed with Demodex recover on their own, once the immune system kicks in. He initially said to watch and if she developed 7-8 places, call him. When she did, we started the invermectin. The scrapings indicated she had dead adult mites, which meant she was fighting the mange, but needed a little extra help, as he put it. One of the other vets said that when immune systems were given out, she didn't get the best one!
I have noticed that a lot of vets begin the ivermectin immediately. When that is done, it is difficult to know if the dog's immune system could have taken care of the Demodex on it's own.
When I felt all stressed an confused about Tae's Demodex, I had a coworker ask her sister-in-law (who's a vet) about how she would suggest treating mange and she actually does start dogs on ivermectin immediately. I guess they all have different treatment preferences!