Hi so as the title suggests, I did a couple runs with 7/8 t2 11ths done and got 125k~ idols, both times to 1320~

I then completed the ApoD t2s i have left including the 8th t2 11th and I am now getting less than 100k for getting to 1350~

Either I was incredibly lucky twice with my 7/8 done, or something is wrong

After having done the second four T2 11's, i have had runs getting less than i did when i'd only done the first 4 T2 11's (always to 1581). Overall, i'm averaging more, i think - though it's not as big a boost as i'd maybe expected.

Fact that the drops are inconsistent can lead to quite a difference based solely on one's luck with just the last three or so boss areas.

It will take someone else to actually do the maths and prove we are getting the bonus % we are supposed to be getting, however - as i have not the requisite skill.

The bonus Idols dropping from a boss, as your fellow players have pointed out, are not guaranteed. It is quite possible that a lot of bosses on your run may not drop extra Idols.