Yet another thing... Just as in medical diagnosis, it's important to have a
sense of probabilities. For example, a defective switch or electrolytic
capacitor is much more probable than a defective low-power resistor.

As physicians say, "When you hear hoofbeats, think horses, not zebras."

Of course there are moments when I say, "When you hear hoofbeats, think
duckbilled platypus"...

....which brings up another point with a medical analogy. Specialists see
disproportionately many rare problems, and they lose perspective on how rare
they are. The general practitioner actually sees the population, without
waiting for referral from another doctor, and is more aware of population
statistics -- but also, perhaps, prejudiced to miss rare diagnoses.