GMAT Strategy

How reliable are they? I just took the free CAT version and scored miserably Q-40, V-24, T-550. Are Veritas exams scoring mechanism similar to Kaplan's? I ask this because my combined score in the two are the same. I also want to add that I am studying quite a bit and have taken at least one exam each day this past week (some were on paper so I did not report those score in my signature; these scores range from 630-670). I think that fatigue is also a factor since the verbal/comprehensive scores in my last few CATS have been negative.

There really is a reason behind my madness. And my practice exams serves two purposes: to build stamina and to expose me to as many different questions as possible so I can build a test bank for a detailed analysis of my mistakes. I rush through a exam without checking my answers and pick the first one that appears correct to me. This saves quite a bit of time and I can usually shave 10-15 minutes each section. My thought process about this is: why waste time checking an answer I did correctly? I am only interested in reviewing the questions that I miss. The one bad thing about this approach is that I cannot get an accurate score to assess my skill level. Is this a smart thing for me to to do?

I am asking this because I am currently capable of scoring between 600-650 range. Under actual exam conditions, I believe that I can improve on this score by reviewing my answers and writing out all of my work to help avoid unnecessary errors.

If anyone has tried this approach, please let me know if it worked for you or what you would do the same or differently.