If for instance, I get 2 snakes from ddd. I would qt them in separate cages in one room.
Then I get 1 snake from bbb. I would qt it in a separate room.
If one gets sick or has something strange going on. Nothing in that room comes out and qt time starts over again, when the sick one is well. You could separate the one that was sick for instance into another room. But qt needs to start when it gets better and the qt on the healthy one needs to start when the sick one goes out into another room.
I am a super paranoid person. The reason is plan IBD. I lost everything 15 years ago. I have seen other people get lazy and sloppy and end up losing their animals.
You can never be to careful. I would use the cages you have, not a rack. Just my opinion.