I have a different view. I believe in a hard knock back in the spring and then cleanup if needed in the fall.
1. Mites double in quantity every brood cycle of (3 weeks)
2. When knocked back to less than ones percent in the spring, it will take 2 to 3 brood cycles for them to get to 1 percent. This buys time to the fall and helps to ensure healthy bees in August for the winter bees
3. The mites left in the fall will more than likely be below threshold, hence less of a clean up, making it easier for products like Formic.
4. Since the mites are knocked back early n the spring, the bees will be healthy for the honey flow bringing In a good honey crop to pay for the hobby or business minded beekeeper.
5. With a good spring knock back, the bees will better handle some of the cool spring illnesses, and the healthy queen and her bees will do well at outpacing mite production.
Economic threshold is 4% . If you have a 1% mid May, by July the mites will be at 4% causing brood damage and lost honey production and a good chance the hive will not survive the winter or come out of winter with a very poor cluster size and poor chance of recovery in the second year. If left unchecked in July it is almost a definite death sentence either late fall or in late January or February.
Just my two cents