AIIMS and PGI recruit post graduate and senior residents at 6 monthly basis. So they have two sessions per year unlike NEET which is an annual exam.
Why?
Probably because they need more work force. Or probably that’s how it was laid in the rules since these two are autonomous institutes and they don’t have to abide by the laws of NBE.
So you can actually give the exam twice in an year. Isn’t that amazing for someone who wants to crack these exams.