Hi makam6,
There's a big difference between working through lots of random practice questions of a particular type (in this case, SC) and taking a FULL-LENGTH CAT under realistic conditions that adapts to your performance - so it's tough to properly assess how strong you actually are in SC at this point.
Since it sounds like you're early-on in your studies, it would be a good idea to take a FULL-LENGTH practice CAT Test; you can take 2 for free at
www.mba.com (and they come with some additional practice materials). That score will give us a good sense of your natural strengths and weaknesses and will help provide a basis for comparison as you continue to study. A FULL CAT takes about 3.5 hours to complete, so make sure that you've set aside enough time to take it in one sitting. Once you have those scores, you should report back here and we can come up with a study plan.
I'd like to know a bit more about your timeline and goals:
1) What is your goal score?
2) When are you planning to take the GMAT?
3) When are you planning to apply to Business School?
GMAT assassins aren't born, they're made,
Rich