That's the beauty about the game, you're not actually beating the game 3 times over
The game has ending A, then you replay the game from another character's point of view and get ending B, then you *continue* the game from the ending B and lead to ending C and then ending D. Ending E is a variance of D (like a choice at the end) but the game has it's own sequel embedded inside the game itself.
I wish more people on PG were fans of the game, it's one of the most unique 'video game' ever. You won't find much games which play like this. Did you think Psycho Mantis reading your card and telling you that you like Castlevania was 4th wall breaking ? Nier breaks the 4th wall 100 times over.
Also, one of the ending has you try to shoot out every one of the credits names as a space harrier style shooter .. and no it's not a fun easter egg like DMC3's ending credits, you *NEED* to shoot them all down to GET the ending itself, it's an active objective .. and if you die a lot in this part of the game, you'r offered help by random PSN player avatars from across the world, they act as your AI companions. I had help from so many Japanese named players in this part lol.
There is so much talent behind the game, it's a shame games like this never reach Call of Duty sales figures.