The best-laid schemes of mice and men: planning fallacy

In his 1785 poem To a Mouse, Robert Burns commiserated with a tiny creature whose home he had destroyed with his plow. He reflected that even the most carefully prepared plans often collapse:
But Mouse, you are not alone,
In proving foresight may be vain:
The best-laid schemes of mice and men
Go oft awry,
And leave us nothing but grief and pain,
For promised joy!
Two centuries later, the esteemed philosopher Douglas Hofstadter formulated “Hofstadter’s Law”: “It always takes longer than you expect, even when you take into account Hofstadter’s Law.”
Modern psychology confirmed the pattern. In 1979, Daniel Kahneman and Amos Tversky introduced the term planning fallacy to describe our persistent tendency to underestimate the time and resources needed for a task. Their research - and many follow-up studies - showed that we underestimate not only the complexity of our projects but also the likelihood of outside disruptions, whether that’s a delayed delivery, shifting priorities, or simply getting sick and needing unexpected time off.
History shows this on a grand scale: great construction projects, movie productions, and scientific projects routinely suffer from delays and cost overruns. But the fallacy also plays out in our everyday lives, when even modest tasks take twice as long as we planned for. For example, writing this topic was supposed to be quick easy, and I was intent to finish it in 20 minutes. However, it took almost an hour. Sigh.
Discussion Questions:

• What has been your most memorable personal encounter with the planning fallacy? How did you adjust or recover from it?
• If the planning fallacy is so universal, might there be hidden benefits to it - for example, encouraging us to attempt daring projects we might otherwise avoid? More generally, is it better to be irrationally optimistic about your undertakings (at least slightly)?