I am not as familiar with ISB admissions, but you run the risk of becoming "white noise" in the INSEAD and Tuck pool since you will be evaluated alongside a very large group of Indian applicants. Where I think you have an edge is in your international exposure and your story is compelling if told in the right way. For example, I like your honesty that you were not necessarily looking for a philanthropic opportunity, but rather general business experience. If you also bolt on a brief bit about what you learned about being philanthropic anyway, it could make for good reading. To answer your question directly, I guess I would focus on packaging your strengths in the best possible way to stand out in the crowd and then apply, with the plan B to try again next year but with a better GMAT. Reapplicants must demonstrate some substantial change in their profile to be a viable candidate, and if you added 100 points on your GMAT it could be the ticket for a reapplicant. So I guess what I am saying is that your risk is low in applying with the 630, since you'd essentially have the same chances next year as a reapplicant that you would if you postponed it until then and posted a higher score. Make sense?
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Bryant Michaels
Admissions Consultant