dvcochran
Grandmaster
I think the short answer to this whole question is, "Because that's how the rank structure works in that organization." We can present a lot of different ways ranks/promotion are handled, or could be. I've yet to find one that doesn't have something in its favor, even the ones I don't personally like.
I don't like hard TIG, though I can see some good uses for it. But in the end, some ranks are just TIG-dependent, and that's how they were designed.
I realized I mis-spoke in a previous post.
I do not agree with a hard and finite TIG. I do strongly agree with minimum TIG. Your post made me realize some people may see them as the same thing. Too easily and too often people think they are ready to promote because they physically know the material, at least in broad brush strokes, and are enticed by "getting that next belt". Somewhere in the process the motivators need to change. Again, part of the maturation process. Introspection is a powerful tool.