The single most important thing you can do to get faster at Sentence Correction is getting really good at anticipating what's being tested. There are only a couple handfuls of things that they test. If you're able to quickly identify triggers that USUALLY point to specific grammar rules being tested, you'll get faster at eliminating the incorrect answer choices. A few examples:
1. If the first word of the sentence is a verb form ("Marked by," "Climbing," "Used in," etc. or a comparison word or phrase ("Larger THAN," "Rarer THAN," "As misunderstood AS," etc.), the first noun after the comma is going to be the actor of the verb or the thing that's being compared. Make sure the noun is the correct one of that the comparison is a valid one.
2. If the underlined portion is really long, there is often a 2/3 split within the last 2-3 words of the underlined portion.
3. If you see a word that signals a list or comparison ("and," "or," "than,"), make sure the list or comparison is valid. Note that these trigger words are short, so they're easy to rush right past if you aren't careful, but they're REALLY important!
4. If there is a non-underlined portion of the sentence that's bookended by commas, see if you're able to reread the sentence ignoring that portion between commas. That's frequently included just as a way to distract you from the fact that the parts just before the first comma and just after the second comma need to be able to flow together.
There are a bunch of others, but those should give you an idea. Go back over all the sentence correction questions that you've missed in the course of your studying and go over each with a fine-tooth comb. What triggers are you missing over and over again. Learn to spot the
triggers that tell you which type of error to look for rather than just looking for
errors.
And two more tips that help with SC pacing:
1. Use process of elimination. Use process of elimination. Use process of elimination. Use process of elimination.
2. Be strict about applying the order of looking for errors: first is whether an answer choice changes the meaning, second is fixing any existing errors (partially wrong is totally wrong), third is making sure no new error is introduced (partially wrong is totally wrong!!), and FOURTH is conciseness or flow. Do not move the last topic anywhere else in the list.