Hi manimgoindowndown,
If your goal is to receive a realistic score result as a way to assess your strengths and weaknesses, then you MUST take your CAT Tests in a realistic fashion (which means that you should take them TIMED). However, if you're just asking about how best to practice 'in general' - such as how to take a 10-question quiz, then you would likely find it best to complete the entire quiz before you check the answers. In that way, you'll be forcing yourself to work in a more realistic fashion (since you can't stop to check answers on Test Day).
Before I can offer you the any additional advice, it would help if you could provide a bit more information on how you've been studying and your goals:
Studies:
1) How long have you studied?
2) What materials have you used?
3) How have you scored on each of your CATs (including the Quant and Verbal Scaled Scores)?
Goals:
4) What is your goal score?
5) When are you planning to take the GMAT?
6) When are you planning to apply to Business School?
7) What Schools are you planning to apply to?
GMAT assassins aren't born, they're made,
Rich