But you understand that the engines use entropy for this; they have to. RNG percentile rolls represent —absolutely everything circumstantial... reduced to a difficulty number. The skill level of the PC is their measure of confidence, and competence to influence and control their situation; the lock picker's understanding of the mechanism, and the use of their available tools... It's the same for a manipulative speaker, and their skilled choice of wording. The main problem with (for instance) thresholds, is that it creates infallible PCs, that are guaranteed success—or to always fail, until they improve. That's not accurate either.