The quick summary is that if you can see coloration on your live rocks, and find some confirming animals like pods, sponges or worms, or algae, any anchored being, then by rule of biology your filtration bacteria are there and we don't need to see spikes in ammonia or nitrite.
But for barren group A rocks, we dose the ammonia and bottled bac and wait and test, and see those ups and downs you were expecting.
Since group B rocks are able to move tanks without losing bacteria, that means people at giant marine aquarium shows can set up instant reefs the day before the show begins.
It means I can clean my reef free of algae as deep as I want to clean, because we aren't going to kill off bacteria unless we dose and sustain a medication. Cleaning is no medication.
That group B rocks continually keep their bacteria means we can do very very handy things and our tanks never recycle, given good command over the process. You can do back to back full water changes for ten months every day as a test for example, and not kill your filtration bacteria. Set means set, you just measured that in your opening post.
I know skip cycling doesn't sound like a big deal but it is. The entire science of pico reefing is built on skip cycle procedures, and if you can control a cycle you can simply make your reef do what you want it to do without loss.
