When we’re asked when something will be done, it’s tempting to answer the question. “It’ll be done on March 32nd,” “It’ll take 182.5 days,” or “We need 15 sprints”. Whether that answer is the best-case, average, or worst-case scenario doesn’t matter.
The answer is fundamentally wrong because using a single value hides the fact that we really meant a distribution of possible dates, durations, or outcomes. The exact value is uncertain. Development may be faster or slower than we thought. What if the tech lead wins the lottery and retires? What if a global pandemic forces us to change the way we work?