Usually they promote based on tests. However, ten years ago I was an i-kyu in Shotokan. We were doing some drills and the head instructor pulled me out last night, ran me through a bunch of kihon and suggested that I might be better off starting several kyu up from the white belt I had on. When I looked uncomfortable, he said he could understand my wanting to get better founding in their basics and I’d be promoted to Orange belt this coming Thursday.
They do just about everything a little different here and there. I know five ways to load a side thrust kick, they do a sixth, I’m familiar with about three or four stance shifts with block to reverse punch, they do a different one. You know what I’m talking about.
They enough kata bunkai to fill three or four books on each kata. They perform several complete kata with all the bunkai and two partners on tests (I got to see a Yellow Belt test the other night). They generally take about a year to get to orange (based on the Orange Belts I know), and I understand why.
I really like them and my wife loves them. It is a great club, I’m in it for the long haul, so I don’t mind working basics, especially as my wife is a lot further out of shape than I am (last time she trained seriously was about twenty or twenty-five years ago).
http://www.planodojo.com/index.cfm?page=12 for their rank requirements. They use all the Japanese routinely, and about 75% of the Japanese terms they use are the alternative ones (e.g. I’d use Yoi for ready stance, they would use Hachiji Dachi).
I figure it will be a year or more before I have flexibility back. At least I’m used to loading roundhouse kicks the way they do once they’ve taught it (I learned to load all of my kicks that way for sparring purposes) and I’ve done the KyoshunKai drills with the blade edge of the shin for kicking, but dang, they have a comprehensive kihon.
If I hadn’t had a couple-three years of JuJitsu back in the early 80s to go with my Judo background, I’d be really lost.
Not to mention, when I started out it was just white, brown and black belts.
Longer answer than you asked as a question. Short answer, almost always promotion by public tests. Even if it is just one person for a low belt. In my case, based on performance in class and in an interview.
The rest of the times I suspect it will be based on public tests.
Since I’m in it for exercise and the long haul, I don’t mind taking it slow. I’d much rather be at a lower belt than my skill indicates than at a higher one. I’m too old to act like an idiot and I want to learn it their way, if that makes sense.