by ManhattanPrepLSAT1 Tue May 22, 2012 9:27 pm
Good question! it's very difficult to say how much of the text you'll need to reread. Often, you won't even need to reread the text if you've done your work up front.
For example, if the question says that the author mentions ______ (line 35) primarily in order to... The correct answer relates more to the purpose of the information than the content. If line 35 is in the beginning of the 3rd paragraph, and the 3rd paragraph is all about providing evidence to undermine the view expressed in the 1st paragraph, then the correct answer will say, "to provide evidence against the view expressed in the 1st paragraph."
If the question is testing content, you may need to go back into the text and then it would be a good rule of thumb to start your rereading a few lines above the line reference (not at the beginning of the paragraph), but stay flexible and you may need to reread more of the text sometimes.
Hope that helps!