i received a private message regarding this thread.

--

in general, diagramming is NOT something you should have to do on every critical reasoning passage. in fact, you should be able to deal with the vast majority of critical reasoning passages without having to diagram them.
diagramming is a tool that you should generally reserve for passages on which you find yourself lost or confused.

** IMPORTANT **
whenever you deal with any kind of printed book about stuff like this, you have to keep in mind that it's a printed book -- in which we have to, well, print stuff.
most conspicuously, this means that we have to take processes that are essentially 100% intuitive -- such as understanding the core point of an argument -- and try to map them onto a printed page. the real point is to develop the intuition, of course, but that's simply not something that we can write in a strategy guide. ("you're supposed to get the point of the argument" -- this is really the main issue, but i think you can see that it's not something we could write an entire chapter of a CR manual about.)

in terms of critical reasoning and reading comprehension, there are exactly zero "facts"/"rules" that you need to memorize, and there are also zero formal processes that you must use.

the end goal is to develop the right kind of intuition. if you already have this intuition, then you are already where you want to be. if you don't, then any tool that you might use, diagramming or otherwise, is simply a means to that end, not an end in itself. keep what works for you, throw out the rest.