I think your aim should be:
How many concepts i can learn and make use of these in questions.
rather than
How many questions i have to do..
PS: I had the same mindset in my last attempt. Trust me this mindset will take you till 700 but not more than that.
My scores and mindset before / after :
540: (Before Exam) Who cares lets give it a shot as i got 96 percentile in CAT, GMAT would be a cake walk.
(After Exam) I think i need to practice a lot. GMAT is different.
690: (After Exam) Damn practice practice.. don't care if i get it right , why i got it right or why i got it wrong.
680: (After Exam) Something's wrong ... my RC or CR or SC. I need to do as many questions from my weak area: RC
700: (After Exam) Cool, I got it even after some 2500 practice questions. I realized what i lack is concepts not the questions
how many i got right.
Next exam is in 11 days ... Hope i can get better than that score.
Hope my experience helps you to understand the key issue.
+kudos if you think its helpful.