The old adage states: "If you ask 11 beekeepers a question you will get 12 answers."
We tend to find this true. Its not because any one of them are wrong. It is because everyone does things a little differently. How we work with bees differs depending on region, types of bees, hive placement, ect.
Every year treatment of mites may change. The way we overwinter bees may change, ect.
Why is this?
Did you know that honey bees may not native to the United States?
The North American Honey Bees was introduced somewhere around 1622 and they arrived via European ships.
They may have been here around 4 million years ago but had since gone extinct. Some fossils were found in the dessert but the exact background and why they were extinct for so long is unknown.
Throughout the years, beekeeping and the hive model changed several times. In 1851 Lorenzo Langstroth created the hive that most beekeepers use today. He understood what is commonly referred to as "bee-space." Bee-space is the 3/8" gap that bees prefer which is wide enough for a bee to fly through but also narrow enough that they will not fill it with propolis. When there is too much room in a hive, bees fill every gap with propolis making it hard for the beekeeper to work.
If you study the history of bees, they can be seen throughout the bible, ancient Egypt and in historical writings. Honey was used instead of sugar in many recipes passed down in families.
So why don't we know exactly how to take care of them?
Over the years other pests, mites, viruses and parasites have been brought in from other parts of the world and spread to just about every hive world wide. An issue that can destroy a hive in one part of the world or country may not be as big of an issue in another part. That is why local beekeeping communities are so important.
In addition to these issues, commercial beekeepers and backyard beekeepers do things differently. Organic beekeepers and those who treat for viruses and mites do things differently. Its unlikely you will ever get one answer for a simple question asked.