First of all, excuse me if my english is not very well.
I've been thinking about the time we have to get the items we get from killing a monster from the ground.
This time is so small before another one can get the item.
With so much players online, leveling on the same map, there are always one that will get your items if you don't get them really fast.
I think the time that only the monster killer can get the item from the floor should be like 10 to 15 seconds.