We don't tend to use numbers. Worm has some good classifications in terms of categories of abilities, but assigning numbers tends to be pretty useless for the aforemost mention. More effective to discuss the direct limitations. For example, "needs to focus." "range of two normal sized city blocks," and "isn't immune to their own power" are much more useful, both in universe and out. We were talking about a syntax based categorization system a long while back, I was interested in exploring that a bit further as it could probably work for building a unifying system. The specifics of the Worm classifications are useful as a starting point, but runs into problems when you transfer it to systems like my hero aca. (Again where the numbers fall short-- in BNHA, you can increase your ability with your own power with practice. That's not true in most, so for the syntax based system to work, you'd need to have the first bits be about defining the specific system, ie, Manton Effect or not (BNHA doesn't, Steelheart doesn't, Worm does-- obviously, since it comes from there), are the origins consistent (usually for everything but comic books), can people have multiple powers). Our rules are pretty loose regarding restrictions, with the limits being placed more on "what makes a good story" rather than "what exists in the setting." Numbers limit that. I don't see any system that uses numbers that actually has a point in including them, as opposed to just trying to sound scientific. I love Worm-- it's a web serial, btw-- but if they don't include a reason for the numbers by the end of it, I'mma be annoyed. The number thing is a pet peeve of mine, in case you couldn't tell, and I love superpower content.
EDIT: TL;DR: We don't use numbers, basically, sorry for the wall of text.