Percentages

This feature, like any other, is an element of the setting, following the same rules as the rest and serving the same purposes. Compared to percentage-based protection, it is practically the same (including in terms of "stretching"), with the only difference being that the concept of "luck" is removed. Relying on percentages is absurd. Moreover, with rare exceptions (so-called specific actions), they all had a percentage chance for precisely that reason – because it was difficult to balance them.

They usually have a hard time anyway, if they aren't too strong, and if they don't kill the target, then they might block the next night, and so on, which is a real problem. In that case, it's better without them, or maybe don't make the roles too strong, I don't know.

If they don't kill the target due to "chance," the result will be exactly the same. Or they might fail twice in a row. Or you might even lose your role with protection because you were unlucky.