Comment by tialaramex

Not necessarily "done or not" because it's narratively unsatisfying to just "fail". Imagine you watch a heist movie and in the last 20 minutes the gang are like "Stealing the master key to make a copy was vital to our plan but we failed" and they disband and that's the end of the movie. Realistic but not satisfying and the dice are for a game, a fiction, so we can just eliminate that unsatisfying result.

Modern systems tend to come up with some more interesting consequences, so e.g. maybe success is the thing the player wanted to do succeeds as they expected, but failure shades from "Small snag" to "Technically it did work, but..." like from "The target's PA, Betty, noticed you take the key, so now you also need to bribe Betty" through "Our copy won't actually work, we're going to need to keep the original and hope the copy fools them for long enough"

Or maybe we have a timing adjustment, success means that you pilfer the key, duplicate it in five minutes like planned and slip it back, mild failure is it takes a half hour and everybody will need to improvise for those extra minutes, and bad failure is you'll need it all night, change your plans to accommodate that.