Drop Rate related to monster life?

It's pretty simple...
1) Retrieve all items that can be dropped, and their droprate
2) Generate a random number to determine whether they drop
3) Some items have quantity as well as droprate, generate the number to drop (mesos, boss pots)
4) Make them all appear over the monster, fly in the air, and land on a viable platform.
5) Check whether they're associated with inactive quests, if so, make them invisible

step 2 can be decomposed in several sub-steps that can help maximizing drop-hunt: e.g. there are moment where it is way more efficient to hunt MM and some moment where it's just wasted time