The straight answer is that it is impossible to say.
There are *plenty* of topics that appear in the PrepCast questions that didn't come up in the 180 questions of the PMP exam that I took, but which might have come up for another candidate or on another day.
I think it's worth bearing in mind that the PMP exam seeks to evaluate your knowledge and skills in hypothetical situations you run into as a project manager, and may encounter in the future. However, you are not expected to be an expert on every associated methodology, of which there are hundreds, so don't let that idea overwhelm you!
Very often, I found that the PMP exam questions were looking to see if one had grasped the fundamental principle that set one methodology apart from another.
I'd say that to prepare for every eventuality in the PMP exam, it's a good idea to read as wide a range of recommended texts as you are able (there are many threads here suggesting the best), be familiar with the Exam Content Outline (ECO), and just do as many preparatory questions as you can using the simulator. When you run into a topic that you know little or nothing about, look it up in the glossaries of PMI publications or, failing that, online, and make concise but usable notes that you can study from. It takes a lot of time and work to prepare for the exam, but that's also what gives the qualification its value. All the best with your studying!
