Are shell decoys worth using for pigeon shooting?

Are shell decoys worth using for pigeon shooting? I got a set of 12 as a present at Christmas but don't enjoy the same success as I do with my usual full-bodied deeks. How do you use yours?

Pigeon Decoys – Walking Pigeon

Northern Ireland-based pigeon shooting equipment supplier Pigeon Decoys has launched the Walking Pigeon, a free-moving, wind-directional decoy.