Re: Ranking systems in different countries
I've found that not only each country, but each association can have a different time in grade requirement for their rank progression. For example, it has appeared to me that reaching shodan, or 1st degree black belt is a quicker progress in my own Tomiki brand, than it seems to be in Aikkikai schools I've visited, by a rather significant ratio. However, what the shodan seems to represent are also different in concept. In Tomiki, we generally look at shodan as sort of the beginning, "OK, now you know the basics." In other systems, I understand it is different.
The slowest I've seen ever is what the BJJ guys do, most averaging something like a decade to progress from beginner to black with steady practice.