Question about drop rate (in specific, waystone)

(Simi ssf)

I was doing some waystone stocking and the 0.3.1 patch hit.

More or less using the Eravin's Crit Lightning Arrow Deadeye build and atlas passive 40 point.

Before patch i prepared a 3+3 tower area with in total 92% increase waystone drop rate on this area. After the new patch, I am using some un-identified rare t15 with additional 2 more drop rate tablet on maps, made some +407% maps, with area lvl 80, pack size 42%+, iiq 27%, my character is lv93. I know this set-up is only beginner-friendly level, but i just got 3 waystone from end-boss.

This happend to me for about 4-5 maps so far, for the most, around 5 dropped.

I am wondering what impact the most in this targetting farming?

area level?pack size? rare amount? iiq in general? or just need to juice the map to "not-beginner-friendly" level?

this is PoE1 forums bruh