SREERUPABISWAS
How important is IR score in applications for ISB, IIMs?
How much should we aim for? I am currently getting 3-4 in my mock tests.
The schools that you have mentioned are very competitive and have a lot many Indians applying to them.
So, you would not want to leave any stone unturned. Aim for a respectable score. As Karishma said, 5+ would be good.
Moreover, IR has been in the picture from many years and I doubt if many people without the IR score would still be applying. So the schools can definitely compare the IR scores too.
Having said this, best way to seek information about a school is the ADCOM. bug them and see if you can get an answer.