I took my GMAT score 2 weeks ago and am very unhappy with my score (660). I honestly don't know what happened, I guess I was just too stressed that day and couldn't focus.

In any case, I am applying to Wharton/Columbia/Ross, was about to pull the trigger on all the applications yesterday but had second thoughts. Now, the Wharton round 1 deadline was yesterday, and the other two are coming up really soon.

At this point, is it really worth it to apply for round 2? That would give me another opportunity to take the GMAT again. I scored in the 720 range on my most recent practice tests.

I don't know your background, and thus how strong you are as a candidate. If you can get a retake data before the decision data for this round, and if you a very happy with your application and consider it well above average, then apply now and let them know the retake date.Otherwise, certainly wait and identify some safety schools too.

The big drawback in waiting for later rounds is that there's usually less and less scholarship money available as it gets later in the application process. It might become a bit more competitive, but that tends to be very unpredictable, and depends on the quality of applications (as well as the number) that they receive in the early rounds. Make sure your application is as strong as it can be, and then worry about timing. But yes, Duncan's right, if you're confident you'll get a better score on the second go-round, apply ASAP and let them know you're retaking.