In my own experience the focus on worst-case is a matter of intellectual preparation. My mind is running through as many of the possible failures as can be ima

In my own experience the focus on worst-case is a matter of intellectual preparation. My mind is running through as many of the possible failures as can be imagined along with responses. When I later encounter a situation that is a close-enough match to a prepared response I can quickly adjust to the reality and act. This appears to many people to be purely improvised and can startle them in the way that you seem to grasp all kinds of hidden issues and avoid the pitfalls, and in some cases there is a lot of improv involved, but it's really a matter of being mentally prepared and having good abstract models. The danger of this kind of "disaster" pre-planning is scope creep. Some people will obsess on every possible bad thing, but that is not an optimal solution. Large chunks of "bad things that can happen" are either entirely out of our control or are a combination of absurdly low probability/far too expensive (of whatever resource) to justify addressing.