You might be wondering what challenges that aren't Broad difficulty are? The answer for most of them is Narrow.
Narrow challenge success probabilities lie in a range from (increment)% to 100%, where the increment is typically 10%. The challenge level has the chance of 50%. For every level above the challenge level, you get a (increment)% increase to success chance. For every level below you lose the same percentage, to a minimum of (increment)%. This challenge system is often used with non-main attribute challenges, like Respectable, Investigating..., Brass Ring challenges, etc.
In April 2021, there began to appear Narrow challenges that use non-10% increments (5%, 30%), and some challenges use an inverted Narrow challenge, where every additional point above the challenge level decreases your chance of success.
Challenge List Generator
template = Template:Calculator/ChallengeListNarrow form = ChallengeGenerator result = ChallengeGeneratorResult param = qualLink|Quality Link|Respectable|string param = diff|Difficulty Level|5|int|1-999 param = step|Increment Value|10|int|-100-100