You don't have to order queens every two years either.
People in the business just like to requeen every year, some in fall and some in spring.
They usually have gobs and gobs of hives.
What happens is this.....
They order say 15 queens, knowing that they're gonna visit several yards to inspect the brood pattern. So, they open the hives, check the pattern and if they don't like what they see, they find the queen, snuff her, and add a new queen, and on down the line, at each of the yards.
That's it. Plain and simple.
On the other hand, if you're hobbiest, and you are producing honey for family, friends and the local farmers market, you can just as well let the bees acclimate to your region/area, allowing them to mate with the local drones etc. Heck, they'll do it anyway, and you can't prevent it.
So it's just a matter of business plan and or personal goals....
Bees have never depended on queen breeders. Only beekeepers.