It is your instructors job to keep you on track. It is up to him or her to train you in the abilities that you need. You just have to shut up and train and you will get there. So you might stay at the same belt for a while. If you do, it is because you need to. And the end product is deeper ingrained skill.
That is not how all instructors function. At my place testing for rank is optional and there are some students who will get to a certain belt and then stop pursuing rank. For instance, there are brown belt students at my place who after getting to brown belt have stopped caring about any further rank advancement. There are of course, some people who go into the martial arts who could care less about any rank whatsoever and my instructor is fine with that, but if you do want to pursue rank it is up to you as a student to ask the sensei about it. The sensei might tell you that you're not ready but it is up to you as a student to ask for the form to sign up for the test in the first place, my sensei expects you to take the initiative on that and if you don't than he just assumes that you don't care to advance in rank. He's good with that but if you're a student who wants to advance and you just "shut up and train," and don't say anything or ask any questions, you will stay at the belt you're at not just for a while but forever, or at least as long as you take that approach.
You don't need a mouth to shut up and train.
Obviously you don't since a mouth is used to do the opposite but I think what you meant to say was something along the lines of, "just because you've got a mouth doesn't mean you can't shut up and train."
The question in my mind is why wasn't your friend already aware of his own weakness when going for first dan...he should not have needed to be spoon fed, and that's a failure on both his and the instructor's part IMO.
As I stated before its the instructor who sets the standards so he knows them best and he knows best how a student falls short of them. Therefore it can be a good idea for a student to ask if they meet the instructor's standards and if they don't what they're lagging behind in if for any reason at all, just to clarify it. A student might find out for themselves that their round kick or whatever needs work but they should still clarify it with the instructor just for good measure and to be absolutely sure. If you consider that spoon feeding and if you can figure everything out yourself why even take lessons in the first place? Why not just be your own Sensei if you can teach yourself everything and you don't want to be, as you put it, spoon fed? To each their own but I see no point in re-inventing the wheel.
I took a tactical shooting class and you could say that tactical shooting is a martial art. You learn stances for shooting, you learn specific techniques for drawing and firing weapons and you learn tactical movement. Anyway, at the class, before we took a break for lunch the instructor wanted the class to ask at least two questions. Clearly they didn't expect us to just "shut up and train." The thing is, taking the approach of, "shut up and train," is sometimes a good idea but its not always the best thing to do depending on what the student wants to get out of the art. I speak from my own experience. One of the reasons I preach so much against always taking the, "shut up and train" approach is because I made that mistake myself.
Anyway, Im getting the impression that like some of the others you just don't care about rank. That's all fine and good but if that's the case than like I said before, some of the stuff I say wouldn't apply to you.