I've tried a few times leaving a rig out overnight with just two pieces of artificial corn and have never had anything, but I have had a fair few when using one piece to tip a boillie. I have very little confidence in it on its own but one of my mates always has 2 pieces on at least one rod and doesn't do too badly, its one of his favourite baits.
It winds me up when we have nutritious boillies for the carp then they go and get caught on a piece of plastic