I have six 1 1/2 year old hens. I’ve only had one broody, a Dominique girl. She held strong against our deterring tactics for a while. Finally, I just made her go cold turkey by destroying her nest completely and not remaking it. It was a few days of glaring and broody-clucking, and her walking around the yard looking like a gray and white basketball, but she stopped eventually.
All my hens are “broody breeds”. I have one SS, two Doms, one BO, and two EEs.
Really, there’s got to be a million influencing factors. Age, breed, temperament, environment, time of year, food, other baby chicks around....(my hen set after a few weeks of having young babies in the house that she got to see when I brought them out on “field trips”. I soon sold them, but...the damage was done. She was determined.)