I have had a similar experience recently. I got a 640 on Kaplan diagnostic (Q49 and V in high twenties). Then I took two PRs and scored 650 and 610. Then two days ago, I took test1 of PowerPrep and scored a dismal 570 (Q48 V21). V21 was not convincing at all. Out of 41 questions in Verbal, I got 27 questions correct.
The question numbers I got wrong in Quant and Verbal in PP1:
o Quant (9 wrong) - 11, 16, 26, 27, 30, 31, 32, 33, 34
o Verbal (14 wrong) - 3, 7, 8, 13, 15, 16, 20, 22, 29, 34, 35, 36, 39, 40
My biggest problem during the test was time management. You can see I couldn't get most of the questions correct toward the end of each section. I was running out of time and I had to rush through almost last ten questions on both sections. I also guessed on a few CRs (time consuming for me) toward the end and moved on. From what I analyzed, I think PP penalizes heavily if you commit mistakes at the beginning. See, I made 5 mistakes in the first fifteen starting at 3rd on Verbal! Another thing I noticed was about "experimental" questions. There were 10 q's on Quant and 11 q's on Verbal that were "experimental". So, I am not sure if most of my correct ones on Verbal fell into "experimental" part. Nevertheless, I was still expecting a better raw score on Verbal. This score just hampered my confidence level and I almost gave up on my GMAT hopes. But, on a positive side, this wasn't the real GMAT test. So, I have time to work on my weaknesses. I have closely analyzed what areas I committed mistakes in and narrowed down to CR in Verbal. I got only 4 out of 12 correct.
I have now started to work on the
OG. I have to focus on timing. I'd really appreciate if anyone has suggestions on how to improve timing using
OG questions. I am planning to get a stop watch as someone suggested on this board and clock every question I work on.