Stretch goals for skill specialists?

[Ulzgoroth]

No planner ever: What I want for this job is 3-5 single points of failure.


I was thinking about astronauts, but this applies to a lot of kinds of better-organized adventure. Unless doing so is absolutely infeasible, every necessary task should have at least one understudy who is good enough to comfortably carry that task for the whole mission.

(That is, I'm rejecting the idea of pushing up the baseline difficulty so that only the ace is good enough. You can do that, but it's not what I'm looking for.)

However, if the understudy is good enough, what does the actual specialist add? What do they do to, bluntly, flex the fact that they're not just good enough to do this job but good enough to be the top pick for it? It's often not obvious, often, how to trade on a surfeit of skill for impact beyond the pass/fail check.