I had to use one because I had one girl that was getting sunburned from a combination of the roo's attentions and from molting. I couldn't get her to keep it on. I actually saw her sister hens helping her get it off.
I bought a baby's dress and modified it to fit her instead. I've had better luck with that.
Alot of folks do use the aprons/saddles and have good luck with them.