Flushes are unnatural and…
Flushes are unnatural and the risk reward is not worth it.
A drain and fill is a different story. I do a transmission drain and fill on my vehicle every year as I own a Honda with CVT transmission.
I also do a drain and fill on my coolant every year the properties in the coolant can brake down/ not perform as well, contaminates can build up/ accelerate oxidation.
This used to be more common but now due to environmental concerns related to chemicals and manufacturers/ dealerships wanting to make money the coolants are claimed to last 10 years. That way your water pump, thermostat or radiator doesn’t last as long.
Manufacturers and dealers have the same incentives as those in the healthcare industry.
Health people and health vehicles make less money. If something happens to your vehicle you trade it in and take a serious hit they fix sell it to someone then sell you another ride.
Learn to turn wrenches and save yourself a fair amount of money.