Reminds me of one bit of game mechanics in the Total War series that seems to be actually accurate in two infamous cases. The game series features assassination of prominent "people" in roles - generals, kings, and even clergy, merchants, spies, and other assassins.

There is a chance of success based upon relevant stats and traits and one of the outcomes is that failed assassination attempts often result in them becoming harder to assassinate as they take more precautions and occasionally show mental side effects.

Now look at Fidel Castro and the clownish job of the CIA's loony toons assassination attempts.

It sounds absurdly gamey at first but assassination resistance may be effectively trainable like immune systems or antibiotic resistance. There is nothing magical about it - the target simply builds up infastructure of countermeasures, deliberately not following schedules, and less physically accessible to anyone unvetted. If in the dirty business of sending assassins in the first place quantity does not have a quality in its own but makes defenses stronger - strategically what is needed is one to do it right.

It makes me think about how very close the assassination attempt on Archduke Ferdinand came to being botched. The initial attempt, tossing a bomb at the motorcade, failed, then as the Archduke was leaving, his driver took a wrong turn, coming to a stop right in front of the shop that Gavrilo Princep had gone into to get a sandwich after learning about the failure of the initial attempt.

Maybe the conclusion is that such plans were inherently unreliable, because people change speed by which they move through museums and cancel appointments.

Makes you wonder. 10~ very close calls is as rare as say 50cent surviving 10 shots. What are the odds?