First of all, GMAT scores and intelligence are not the same thing! The GMAT only measures a very narrow/particular kind of intelligence.

You didn't tell us exactly when you took these exams, but my guess is that you're taking them too soon. My very broad rule of thumb: it's unreasonable to expect score gains of more than 10 points per week. So when you got a 580 and took the test again less than 3 weeks later, a 20 point increase is pretty decent. If you take it again in another 16 days, a 620 would indicate good steady progress.

As to whether to reinstate your score and apply now... that really depends on the schools. What are the average GMAT scores for those schools? If a 600 is well below the average, do you think the other aspects of your resume put you ahead of other candidates? Call the admissions departments and ask - they'll often be candid with you.

If you decide to take the GMAT again, here is some advice:

- don't sign up to take the test until you see a 650 on a practice test. That way you can go in on test day confident that you can hit your minimum target score.

- you didn't mention how you were studying. It's likely that you haven't been studying effectively, especially if you ran our of time on the verbal section. Use this forum and the Manhattan Prep blog for general study advice: https://www.manhattanprep.com/gmat/blog/
Do not just focus on memorizing content or doing problems! Locking down timing & strategy are equally important.

- ignore percentiles. They are misleading. Schools just want the GMAT score to help tell them if you can handle the coursework. https://www.manhattanprep.com/gmat/blog ... mat-score/

- the other aspects of your application are more important than your GMAT. Make sure you're working on your essays and resume - and getting solid recommendations - while you're studying.