What I do is not treat. For nothing EVER.
What ever, but that is the worst habit to treat varroa.
You have in USA winter loss reseach. Those who did not treat hives, lost 66% out of hives.
In France it was researched varroa tolerant and treated hive honey yodels. Treated hives got 100% better yield.
Last year, I went into winter with 14 hives, at the end of January, I had 16 hives, got 2 swarms in January.
In February, my hives were expanding so fast that I was making nucs because I was afraid they were going to swarm. 4 weeks after pulling 3 to 6 frames from every hive and adding supers I still had hives swarming. I made the mistake of not putting the old queens in the nucs.
Out of 19 hives I now have (we sold several nucs), 2 hives have light mite drops. One of them is my largest hive and biggest honey producer. The rest, it is hard to find a mite in a clean, dry oil pan. SHB population is also very low, especially compared to thee thousands of SHB I was killing the first 3 years in every hive. That is why I am leaving the oil pans dry.
A lot of these hives are from feral hives that had to survive without any assistance. They groom each other and remove the pupas that are infected with mites.