This is a difficult topic. My organization generally
ranks by training "span" rather than
training hours in class. To earn a black belt, you
need basic proficiency in all of the arts and a few years
of teaching time. All of that takes about eight
years of training in a regimen of 3 classes/week.
You are promoted only during triannual ceremonies.
If you miss the ceremony during a fellow student's "time", you may be passed up. The black belt degrees don't have any definitions other than a rough time estimate, leadership ability and teaching experience. Overall, it seem to be an accumulated value
to the organization rather than technical ability. In retrospect, I think this is wise. Martial arts should be a personal pursuit. The fixed time
ranking avoids petty competition for rank. I've
heard of all sorts of systems:
1) explicit requirements,
2)bringing a beginner to black belt (for 2nd degree),
3) yearly spacing depending on the degree (after
black belt, two year for 2nd, three years for 3rd, etc.),
4) promotion when you start your own organization
so that you may promote your own students.
5) You must defeat everyone at your current rank in
combat
Personally, I would define a black belt to be
someone that has a basic proficiency in the core
art, is able to teach all of that material with
rudimentary teaching skill and is able to deliver
crippling blows. The last requirement is quite
severe and selects for larger, stronger
students. I do have a philosophical problem with
that because I've always believed that technical
training should help equalize a relative disadvantage
in size and strength. However, that means that
students of below average size/strength will need
a significantly higher level of technical/tactical ability.
Thus, it's difficult for me to compose a definition of
a black belt because it's the final result that counts.
In a modern society built of a supposed meritocracy, it's difficult to resolve explicit rank for activities in which we've presupposed that rank is a specific indication of
technical ability. Yet, we live with many examples of such and don't question them.
A prime example is the US educational system.
Until age 18, just about everyone is advanced by
age in the K-12 system. Most of the kids never
learn much more than that offered in the
3rd grade. Everyone is graded. Just about
everyone graduates even though there is a HUGE
difference in the quality of the education.