I am considering training with an Isshin Ryu club near were I live. It is a husband and wife business. From a student in the class, I have learned that within the first 8 months of training, a student reaches their 4th belt; they get promoted very quickly. There are no exam days. When a student is "ready" for a promotion, time is set aside during class for a small test. The 4th belt test which for them is blue consists of answering questions and doing one kata. By the third belt they are considered intermediate level students.
I took shotokan and the time between each belt was much longer. Are promotions quick with Isshin Ryu? I am considering joining this club.
It is difficult to answer your question. Isshin Ryu is not a hierarchical system with a set of standards and a single set of rules at the top, like some types of martial arts are.
There are several major branches in the USA, more branches in other parts of the world, and plenty of 'stand alone' non-affiliated Isshin Ryu dojos. I am not qualified and will not attempt to say what is right and wrong with regard to any Isshin Ryu system or dojo's method or timing of promotions; it just would not be appropriate.
I am a life member of the UIKA and I am a 2nd degree black belt under a well-regarded and known instructor. In our dojo - and I am ONLY speaking of our dojo - promotions are based on various criteria. In some cases, the criteria is adjusted to the student, at the discretion of our head instructor.
We do not have testing that is as formal as some other schools, true. We do not charge testing fees and the only belt fee is for the actual cost of a new belt if the belt color changes (kids get stripes in between color belt changes, there is no charge for that).
For adults, the 'typical' promotion period from white to black belt would average about 5 years, at my guess. I could be wrong, but that seems about right. Kids do not get black belt, brown is as high as they go until they are 18, with very few exceptions. We do not have junior black belts, a black belt is a black belt.
Our adult belts are white, orange, green, blue, and three degrees of brown. One might generally (very generally, nothing carved in stone) to advance to brown belt within two or three years. Then they are brown belts for a very long time.
We consider green belts as intermediate, and brown belts as advanced.
I hope you find this helpful. Again, this applies only to my own experience in a UIKA-affiliated dojo and I would not consider it valid for any other Isshin Ryu school or even for a UIKA school if they have different criteria for promotions.
One last thought is that promotions are not really all that relevant in the long run. One either can or cannot do karate well. Belts hold up pants. There are certainly schools that offer guaranteed promotions with signed and paid contracts, and if one wishes, one can buy a black belt promotion online from a variety of sources. I would posit that they transfer no ability along with the title, but different people want different things, I suppose.