Hi aspirant,

There is no such drawbacks if you directly apply for the second or third round without applying for first round. You can register for each round as a fresh candidate. The only disadvantage is that, the students applying for first round would be allotted  top colleges as per their preference. So, the seats of top colleges might get filled up by the students who have got a good score and have appeared for round 1 of UPSEE counselling.