Star Trek

I'm sure that if we are able to build a photon torpedo in real life, it would be nearly impossible to get even 80% of the antimatter to react but since Star Trek isn't real life we can assume that their photon torpedoes are 100% efficient or at least very close to 100% efficient. It's just like with any other science fiction, its not supposed to be completely realistic and unless there's a huge flaw in their science that cannot be explained at all like with human batteries in the Matrix, we can assume that everything they do is under ideal conditions and that random chance always swings in their favor.