A teacher who lives here once said If you bypass Medal Dancing you will eventually have to go back and learn.
Also learning a Medal one to one is not a good way to go. Even if the teacher gets you to do whatever is being taught solo. He has no way of knowing if you are using your feet correctly when you are in a Ballroom Hold. One to look for , for the lady is after a Spin Turn which finishes with a TH. The next step into 456 of a Reverse. How often do we see something that barely resembles a heel lead. Medal classes is the way to go. The stricter the teacher the better the class will be.
This is how Sydney Winter ran his classes. We learnt the group. Then each had to do the group just taught on there own. Both girls and boys solo.If anyone was having trouble they went to Ted in Dunces Corner where they stayed untill they were up to par.We would pair off and each pair would be on the floor on their own under the very watchfull eye of Mr. Winter. Some little time before the Medal was the time for a couple of private lessons. Not everybody got to do the medal. Sydney had a big reputation to uphold. If you weren't nearly perfect you took the class again.The last Medal I took there was judged by Henry Jacques who was British Champion at Blackpool three times running. The medals in those days were made of Bronze, Silver and Gold was gold plated. The Medal was always danced with a teacher even though we had our own partners.

I don't know if I can be of a lot of help, but I am currently in Bronze. When I started taking lessons in the Bronze level I asked my teacher how long it would take to go through Bronze and his response to me was that it would take around 300 lessons. I take one lesson a week, you do the math. If I choose to be certified in Bronze then I would have to take an exam after a certain number of steps that I had learned. Such as the step 1-10. Then later another test on step 10-20. etc...I'm assuming that you would have to go through the entire Bronze syllabus, knowing both parts of the dance. After you went before the certification board and could pass their requirements, then you would be able to teach Bronze Level.

I agree with those who indicate that it depends on the individual and the studio at which you are learning. I think it is great to have set goals in mind and a time frame for achieving it, but in some cases, and some places, you'll be reaching those goals without even really knowing it. I have been at the same studio for four years now and the first time I even thought about the competency level was when my instructor said, "Now you are doing silver level brush and feather steps." To be honest, I didn't know, or even really care, what he meant by that. I just knew I was getting better and learning some really cool stuff.