B-schools start filling up seats as soon as they get good candidates. So it is possible that in Round 1 itself, more than 50% of seats are taken. Also, as far as scholarships are concerned, only those who apply in the first or second round deadlines may be eligible. as per the b-school policy for international student scholarships. Moreover, most b-schools discourage candidates from applying in the last round, because it may not leave them with enough time to complete visa and other formalities.
At Sharp Minds, we have had students who have made it to the likes of Harvard and Insead by applying in later rounds, so there is no compulsion to apply in Round 1 only. A strong candidate will secure admission in any round,