A question about waitlist semantics

I've noticed that a lot of threads refer to "a lot" or "little" waitlist movement. However, I was wondering...does the amount of waitlist movement refer to numbers (for example, more than 40 ppl) or does it refer to the amt of movement relative to the class? Also, what about the amt of movement relative to their waitlist system? In other words, do schools that get through their Tier 1 have "good movement" and those that don't get through the upper tier have "little movement?" Ok, these were just some random questions and I was wondering what ppl thought when they read terms like these...

Thanks