I think that it is impossible to present any 100% correct info about loot statistics of these bosses, bacause none of fansites doesn't present it. However I killed both - Lisas and Bullwarks quite a lot of times, so all I can do is to share my experience.
Our first Lisa's Doll was dropped soon after whe've started to kill this boss. I'm sure it was less than 50 Lisa's.
The same story is about Bullwark. We've killed albout 50, then we dropped our first One Hit Wonder. Some time later we looted another One Hit Wonder. I think that in total it was about 250 Bullwarks to loot 2 clubs.
So in conclusion, I guess that the drop chance is much higher than in case of pharaohs, for example.