Ye so i can shed some light on this, i go to Alnoori MS (the one ranked 5 for maths) currently doing extension 2 and i did bio-accelerated in 2022 (got 95 in that) , and ye all the private schools like my one and alFaisal have a entrance exam to get in.
On top of that they force a bunch of kids to go adv or standard if they know they cant do ext1/2 well + they have massive maths-adv accelerated classes (like 30ish kids) that all just do maths 24/7 and hence all these band 6's.
+ Alfaisal maths adv/ext1 and 2 teacher is absolutely cracked, like man breathes maths (Mr Jamal)+ their internal assesments are absolutely crazy
The alnoori adv maths teacher is also cracked
+in Alfaisal can only do ext2 if u got a band 6 in maths accelerated in yr 11
+The pressure is insane, you finish all content by mid term 2, and trials are in term3, so u have about a little over a term + Holis
to just do past papers and usually get thorugh 30-50ish papers just for ext1/2 before trials even start.
IK this bcuz i go to the same tutoring centres to the Alfaisal kids, and im telling u their ext2 class is absolutely not normal.