What a great question you ask, and as it turns out, I am going have you answer it yourself.
This is something that I discuss with my classes. I tell them that on critical reasoning and certain reading comp questions - but NEVER sentence correction - that it is possible to stop when you know the correct answer.
This is something that you would do on a problem solving question on the quant section right? It you find that the answer should be 127 then you stop when you have found that answer. Strengthen questions, weaken questions, and resolve the paradox are question types where you can often do a very good job of understanding what the correct answer must say. And when you find that it is possible to stop and move on.
Here is how you are going to answer the question for yourself. Whenever you do select an answer WITHOUT reading all five choices you should draw a black line under the last answer choice that you read on your scratch paper on the A B C D E written vertically for that problem. If you do not write out A B C D E for critical reasoning problems then you can just make a note on your paper "prob 5 B/" or something like that. Anything that makes it clear to you which problems you answered without reading all five choices.
Now, when you are looking over these questions, you can see how you perform when you stop reading after you have found what you are looking for. How do you perform on these questions as opposed to others? Are you more likely to get the question right if you do this? It will be up to you to evaluate the results and decide what works for you.
Just on a personal note - I do this in practice, because we do so many more practice questions that we ever do questions on the actual test. I will stop at A or B or C or D if I think that is correct. I will even do this on a practice test. It saves time and it keeps me sharp. But on test day - you are looking at only 11 to 13 critical reasoning questions and even when I am certain that I have the correct answer, I do just glance at the other ones because each question is too precious to mess with.
I would not advise that you "stop at A" if you are hoping to save time. It does not take very long to read the rest of the choices and the time savings is not worth it. A better reason to use this is if reading on actually confuses you and makes it less likely that you will get the problem right.
Those are my thoughts, but the final answer is up to you!
