Frankly, if you are not yet already familiar with the environment, I would be skeptical of a "rapid-track" course. It might not be intended for your particular situation. It might gloss-over things, assuming that you already have a certain background, such that if you
don't have that background you might not know ... that you don't know.
Again: If you're going to educate yourself, whether you take a class or self-educate, beware that maybe "you don't know what [it is that] you don't know."
The
bottom line is that these courses are designed to present you with situations that mimic on-the-job. You are required to correctly assess the situation, come up with a strategy, and resolve a problem and/or accomplish a task. By whatever means, you should
practice until you are, indeed, competently able to do that. (Thereafter, "actually getting a piece of paper," or not, is really up-to-you.)
As they say, "so he read a book on swimming ... and then he drowned."