Years after the movement to obtain civil rights for black people in th

GMAT and LSAT passages are similar in difficulty but GMAT passages are usually not this long. We have short and dense passages in GMAT.
Considering that we have slightly less than 2 mins per question in GMAT and that CR questions often take 2-3 mins per question, it does make sense to stick to the less than 2 mins per question rule. Of course, first 3 or so mins will be spent in reading the passage but then every subsequent question should be answered in under a minute. You would normally have 3-4 questions from a passage so that would add up to about 6-8 mins.
How much leeway, if at all, we have in case we are working with LSAT RC questions will depend on the question so I cannot give you any guidelines for that.
To get an accurate sense of your speed and time management, work on some official GMAT RCs.

To increase your reading speed, practice reading faster every time you need to read anything (not just while doing GMAT questions). There are some bad habits that we develop over time such as monologuing which we must consciously try to avoid. Do know that increase in speed takes place but not in a span of a few days. It needs consistent practice of a few months.
Also, try to improve your verbal question solving skills. That will automatically lead to some improvement in time management.