Jake:
I have attended the North American Longbow Safari for many of the 30+ years it has been held, including the first one. 3D commercial foam targets have been the standard at most of these shoots. It has been a broadhead shoot with up to 60 targets over a 2 day time frame. I have seen very few broadheads pulled off inside the targets over the years. It seems that making sure the interior of the ferrule is extremely clean helps to keep the head on the shaft. I use a small propane torch to install ferruled heads and always run the flame up in the ferrule for a time before placing the head on the shaft with quality hot melt glue. That being said, remember that commercial 3D targets are made from a "heavier" foam to help with longevity and therefore will "hold" the point more than regular styrofoam. And 2 blade heads can be removed from the target much easier than multiple blade heads. Tapered raw wood without finish seems to help hold heads on also.