Maybe this will help:

Most people think of PRR as non-linear, and the damage reduction part of that is true:

However, if you look at the EFFECT of that, you will see a linear relationship between the amount of PRR you have, and the damage required to kill you. The damage mitigation isn't what matters most. What matters most (to the monster trying to kill you) is how many HP of damage does it take to put you down?

So for every point in PRR you get, you are linearly increasing your chances of survival.

Say you go from 0 PRR to 20 PRR. Your damage mitigation is now 16.67%. Now it takes 1200 HP to kill you (if you had 1000hp to begin with). So that's an effective increase of 200hp.

Say you go from 20 PRR to 40 PRR. Your damage mitigation is now 28.57%. (Doubling PRR did NOT double your damage mitigation percentage). BUT WAIT. How much extra damage does it take to kill your 1000hp toon?

**1400hp!!!** That's an increase of 400, which is exactly double the amount from before.

The moral of the story is: Doubling your PRR doubles the amount of

**extra HP** it takes to kill you, which is all that really matters. It does not double your damage mitigation percentage, but the survivability effect is purely linear.

So, every point of PRR counts, even at very, very high amounts of PRR.