I think it depends on how much you are aiming for in the real exam.
FIITJEE aits are controversial for conclusions . Even fiitjee teachers recommend not to give exams . Exams are also very hard , almost all question of advanced exams are out of syllabus.
Don't panic with the marks of advanced test but do compare your mains tests .
Also if you want to compare you can compare with you batchmates or you can search past threads in which ranks were discussed also you can see what rank those people got in final exams . I will attach my result of all tests in some days .
It depends on a lot of factors.
When I gave AITS, my rank varied from 1000-6000. My average rank was around 3000. (If i remember correctly, I'm not very sure)
My professor told me that your JEE rank is usually 5-6 times the rank that you get in AITS on average. According to this, my JEE rank should've been around 20000. In reality, i got somewhere around 3000, which was approximately my AITS rank.
So that's why I'm saying that it depends on a lot of factors. Maybe I gave the exams just for fun, but if anything, i felt like giving the exam was not useful, as it was a big waste of time (>10 hours would go in that on the exam day.). I stopped giving the tests after a while.
I recommed that you give the AIITS though, as the difficulty usually matches with the actual JEE.