This is a RNG guide that deals with the question how much time you can lose due to bad RNG in AI Nightmare Any% runs.

The final result shows that a bad RNG run will in total cost you 73 seconds time. There is only one spot - Mission 7 without a flare or stun - where you can die due to a very risky strat. Even this strat can most of the times be mastered by practice. There are no inevitable run killers in Alien: Isolation. Compared to the total Game Time and the margin for error still existent in the top ranks, even with completely bad RNG a top rank is still possible.