I have often pondered this problem with respect to some of the traditional heuristics and biases studies, e.g. the "above-average driver" effect. If people consult their experiences of subjective difficulty at doing a task, and then guess they are above average for the ones that feel easy, and below average for the ones that feel hard, this will to some degree track their actual particular strengths and weaknesses. Plausibly a heuristic along these lines gives overall better predictions than guessing "I am average" about everything.

However, if we focus in on activities that happen to be unusually easy-feeling or hard-feeling in general, then we can make the heuristics look bad by only showing their successes and not their failures. Although the name "heuristics and biases" does reflect this notion: we have heuristics because they usually work, but they produce biases in some cases as an acceptable loss.