Glad you find them helpful. :)
You mention "OG RC." OG materials are
practice materials, but not
study materials - they will not actually help you learn how to get better. There are no strategies for how to read, how to prioritize kinds of information, how to answer the different question types, what the trap answers tend to be like, etc. So it sounds like you do need to identify some study materials that will help you with RC.
Here are some to get you started:
http://www.manhattangmat.com/blog/index ... p-passage/http://www.manhattangmat.com/blog/index ... -passages/http://www.manhattangmat.com/blog/index ... -passages/3-part series on one passage (with 2 questions):
https://www.manhattangmat.com/blog/inde ... -passages/https://www.manhattangmat.com/blog/inde ... m-passage/https://www.manhattangmat.com/blog/inde ... m-passage/Yes, I'm sure you were mentally fatigued and nervous - we all are when we take a test! :) That'll be one of the things you practice to overcome.
Re: your question about taking a class, there are plenty of people who succeed studying on their own and there are also plenty who are very happy they took a class. It really depends upon your personal circumstances, level of motivation, and ability to push forward yourself (vs. with the help of an expert).
As a general rule, it is less expensive to work on your own but that can also take longer, because you don't have the same level of structure and expertise from an instructor. For many people, this trade-off is worth the savings.
It is more expensive to take a class but, if you identify a good program with a teacher who communicates well and knows his/her stuff, then your study will often be more efficient.
Taking a class / doing something more structured is also a good idea for someone who is very busy with work or who is worried about losing motivation or slacking off.
Good luck - let us know how it goes!