Rather than quote 3 posts, Iāll just quote one.
The belt, up to a certain point, is supposed to be indicative of skill. And other things as well. When you get up there in rank (and usually age), youāve proven your skill. From some point on thatās different for every school, rank is about your contribution to the art rather than your own skill. Get up to, say 7th dan and itās all about spreading the art and advancing it one way or another. And promotions are based on that rather than who you can beat up.
Kidsā ranks transitioning into adult ranks are handled very well in my organization IMO. The curricula donāt match up; junior black belts are somewhere between 3rd and 2nd kyu adult syllabus. Kidsā belts have the white stripe going the length of the belt. When a kid becomes adult age, they wear the kid belt and are taught as adults. They wear the kid belt until they earn the comparable adult belt like any other adult would. Junior black belts do the same, but they test for adult black belt like every other adult when theyāre ready.
Iāve seen my CI test kids for the comparable adult belt and simply promote them to it during class. It depends on several variables and I completely agreed every time. Itās usually dependent on the kid and the timing.