isnt goldcharm flawed????

if u get the 20% rarity buff after killing a rare it doesnt count to the kill or not since u already killed the rare and package sent to server for the kill with your current rarity.so whats the point having this since its like almost impossible to kill next rare in like 1 sec or even u boost the buff time up its like maybe 2 seconds,doesnt this make this charm kinda useless?