"On all skill checks, npcs roll a d20. On a 20, they actually roll a skill check. Otherwise, they take 10".
...
Thoughts?
The faster way to do the same roll is, "On all skill checks, NPCs roll two d20s. If the two dice have the same number, that's the d20 roll. If they have different numbers, the roll is 10".
I go with the simpler: if the results of success or failure aren't interesting, no check.
So no one makes a check to climb a normal ladder under unchallenging circumstances.'