I'll offer what I have learned, since I do not see any replies yet. Please keep in mind that I am VERY much a newbie with this.

From what I learned during my Empower course on IR, you should "skip" any questions that are going to take a long time to calculate. Usually, these are the algebra formula- based calculations. Multi-source reasoning can also take a lot of time; however, I have read that MSR questions carry more weight towards your IR score than other questions, so skipping these may be a more risky strategy (at least, from my point of view). However, if you are getting tangled up in any question so that you exceed 3-4 minutes, I recommend taking a guess and moving on.

If you read the IR "what-if" scenarios, you can miss a few questions and still get an 8. So like anything, identify your weaknesses so that you can avoid losing time there.

It has helped me to practice and to time myself on each question. So on some questions I needed 2.5-3.5 minutes, and on others I only needed 1.5 minutes. That should give me enough time overall, keeping in mind that I will dump 1 or 2 questions on purpose. It's essentially the same strategy that we use for Quant and Verbal.

I hope this helps.

CSmitty thanks for the reply. I too had read about skipping questions but I think if you end up skipping "real" questions and answer "experimental" questions, then the result wont be good. I am trying to apply same strategy as other sections - skip if a question is taking too long and move along. I found the IR section in the GMATprep Practice tests little easier than Manhattan Prep tests. Although for some reason GMAT practice test gave me same questions for both my tests, just with different order!

I am also planning to do more practice tests for this. Thanks for the help and good luck!

I found that the trick with IR was the amount of information given compared to the 2.5mns to solve the question.
My technique for IR was :
1. Start reading the question first and not the documents or graphs you are given. This way you know what you are you looking for.
2. Don't read all the document / information. Now that you know what to look for, just focus on it. Sometimes you need to read a bit more context but most of the time you'll just have to scan the document quickly and read with attention the parts that interest you.

Let me know if this makes sense or not . Good luck!