Rolling Unawares, Rolling Alert

I’ve written many times about my simple way of handling both skills and saves vs. natural or mundane situations: roll 5+ on 1d6. Very simple. But sometimes, I’m rolling to prevent something bad, and other times I’m rolling to undo something bad. One is better than the other. So how should the GM decide which to use?
I think I’ve come up with a clearer explanation:

If a character is alert (knows the danger,) the character avoids it unless the player rolls 5+ on 1d6.
If a character is unaware, the character can still escape danger if the player rolls 5+ on 1d6.

Example: Arrow trap. If the character can see a hole and the player says, “I think something’s going to shoot out of that hole. I’m being on my guard,” then there’s only a 5+ on 1d6 chance that the arrow hits the character.
If the character is stumbling around in darkness and has no idea there’s a hole in the wall, when the trap is triggered, there’s a 5+ on 1d6 chance that the character dodges the arrow.
Ability scores affect whether there is a roll or not, of course. My current thinking is this:

Score	Unaware	Alert
Worst	Fail	5+ or Fail
Standard	5+ or Fail	Fail on 5+
Best	Fail on 5+	Succeed

Worst here means an ability score of 3 and Best means a score of 18 (on 3d6.) Naturally, if a particular score is not rated on the 3 to 18 scale, these numbers would be different. There is no roll on either a simple Fail or simple Succeed result.
Some situations can adjust how either “Worst” or “Best” are interpreted. I would just write “Easy (15+)” to lower the minimum score needed for the Best result, or “Hard (6)” to raise the maximum score that counts as the Worst result. You could note which ability score is being checked, but I would just go with whatever seems right for the situation, because sometimes a player may have a good argument why they should be allowed to use other abilities.

This work is licensed under a Creative Commons
Attribution-NonCommercial-ShareAlike 4.0
International
(CC BY-NC-SA 4.0) license.