I felt like I might add my two cents worth to this discussion because learning styles especially in economics is something I'm really big on with all my students. In short though, I definitely agree with the previous two posts that spamming practice SACs like in other subjects is not the way to be going about revising (unless, and only unless you are having trouble finishing within the time frame).
You will never truly have revised everything they can throw at you in economics. By this, I mean that there will always be a new way of putting a question to you, or a new idea, factor, concept etc. that you might not have heard of before, or be completely familiar with, therefore doing lots of practice SACs will not cover everything.
This is what I would do:
1. Read, a lot! I know this isn't considered a very effective way of learning content, but the reality is, so do well in economics, you have to be well read on a broad range of concepts and issues so that you at least have some idea of how you might tackle something you haven't necessarily seen before.
2. Learn your fundamental concepts (basic macro etc.) to the point of absolute mastery. As I said in the previous point, you might get something you've never seen on an exam/sac, but if you've mastered your concepts properly, this shouldn't pose any additional challenge. You would just apply the same method of thinking you've developed in your conceptual mastery process.
3. Figure out a solid structure and method of responding to questions and make sure it doesn't have any holes in it. In economics, you get marks for logically and clearly stepped out responses.
@siddhartharora: Out of curiosity, what sort of things were you losing marks on? I might be able to help you if you let us know what things you weren't necessarily getting right.