It is probably a better idea to wait and take the second GMATPrep nearer to your test date if you have one already established.

You want to have your techniques down solid before you take the GMATPrep again.

There is some possible overlap between the OG books and the GMATPrep test but do not let that case you to lose sleep if you get a question that you have seen, just let the clock run and go ahead and answer correctly.

n/a

You can take other, non official tests in the meantime if you are looking to improve your speed, time management, etc - just remember to take those scores from those tests with a grain of salt!

you can also take tests in the GMATPrep multiple times by uninstalling and re-installing again.
Read the article, Taking the GMATPrep Tests Multiple Times for more clarification https://www.beatthegmat.com/mba/2010/03/ ... iple-times

It is possible to "reset" the GMATPrep software to some extent by reinstalling. However, there is almost universal agreement that by the 3rd retaking of the exam you will likely be seeing enough repeated questions to mean that your scores are unreliable. This does not mean that some people do not keep taking to try to "see" all of the questions.

Unless you are installing different versions of the test reinstalling does not mean a new pool of questions. In the article mentioned it says that if you do not remember that answer your score is still valid. I disagree, even if you do not remember the answer to a question, if you have seen the question you will still not be confronted with something brand new that you have to figure out.

In short, attempts 1 and 2 of each test scores are reliable, attempt 3 can be worthwhile to see new questions, but score not as reliable.