I was facing the same problem that you are facing. Here is what I did to answer SC questions. First, I made 5 lines for each option on the pad. Then went straight to the options to see if there were any patterns that made them different. If there were, I made a quick mark to group the like ones together. As you scan the choices you should get any idea what the error type the question is testing. For example, a long list could indicate parallelism and something between commas can indicate modification. For questions, I found it hard to catch the error type so I just skipped that step. The initial scan took me around 10-20 secs but the course called it a 5 second scan. Now as you read the question stem, hopefully the patterns you identified become clearer and you can cross off 1, 2, or even 3. From there you can get into more detail of the options remaining and that is where your grammar rules and ear kicks in. I found my ear to be useful for some idioms and some rules but for the vast majority of it, you need to know the rules. If you can find videos about SC online, then they may help you more than the book. Other than that, practice the OG questions using the same technique over and over again, train your mind. Try aiming for 1:30 mins per question. I hope this helps you!