Dead Rising/Saint

In order to acquire the Saint achievement Frank must rescue at least 50 survivors in a single playthrough of 72 Hour Mode.

The most survivors possible Frank can save is 53 of the 54 survivors. Frank can NEVER save all 54. Either Dr Barnaby or Sophia (I think) must die.

This is one of the most challenging of the achievements. However, in order to get 50, you must fail the cases in the game, and I'll explain why. There are only 47 survivors that you can rescue in the mall. The other survivors must be Brad, Frank, Otis, Jessie, the chopper pilot and Dr Barnaby. To save them, you must fail case 6-1, then finish all other scoops. If you complete the cases, certain fates await Brad, Jessie, Dr Barnaby and the chopper pilot so fail case 6-1 to get "Saint". With that in mind, it does mean you can miss three survivors in the tight schedule and still complete the achievement.