I was a Cho Dan Bo in Tang Soo Do which, while different from my current style isn't that different from the ITF style TKD I currently study. That rank is between 1st Gup and 1st Dan. At my current school, that rank is called Probationary Black Belt. Though my certificate from my old school is packed away someplace, my old school can verify my old rank. A little over 5 months ago, I started as a white belt. I am currently a green belt, on track to test for 5th Gup, or high Green at the end of the month. I have already gone past a bunch of people who were yellow and high yellow belts when I started.
That is my teacher's philosophy. I am fine with it for a number of reasons. One, I still need to learn all the TKD patterns up to black belt, which is 12 to 14 forms. In addition there are things school specific including 13 basics, 20 one steps, 6 linear forms and 20 sparring combinations. It is very manageable to do this over a period of months, as I quickly move up the ranks.
The other thing is, if my current teacher gave me back my old rank, it creates a problem. At my current school, probationary black belts usually test for 1st Dan 6 months after making probationary black belt. Rarely, students extend that to a year. At this point, if I got my old rank back, in theory, I would be expected to test for 1st Dan by December, and I don't think I would be ready to do that yet. So I am fine moving up the ranks fairly quickly. At my current rate, I will make 4th Gup by November, 3rd Gup by the end of the year or early next year, and Brown belt by the Spring, or about 14 to 15 months out from when I first started back. At that point, I will need to see where I am at. I can see a path to Brown belt, as I already can hold my own in sparring against some of the adult brown belts at our school. But I have a lot of work to do to get to the black belt level. My self evaluation tells me I am not there yet.