Here's my untested, unproven, I-just-made-this-up-but-it-sounds-pretty-legit guide to mastering SC. Procede at your own risk.

(SC is my best area so I'm not actually studying like this.)

1) Before jumping into all those practice questions, do a thorough review of everything the GMAT tests on SC. This probably involves getting an SC-specific book, which you may have already done. If you have, you may want to go through it again since it's your weakest area.

2) There are only so many grammar rules the GMAT will test you on, so they're each going to come up a LOT in 1000 questions. Don't just chug through all those questions, because repetition alone won't help if you don't understand the concepts or what you're struggling with. Instead...

3) Do the questions in smaller chunks (maybe 50?). After each chunk, go through and make a list of what grammar rules you had problems with. Study those some more before moving onto your next set of questions. That way, you can focus your studying on what you're having problems with and you won't waste time reviewing concepts you've already mastered. You may find that you've mastered everything before you get through all 1000.

Good luck!