Why estimating user stories in man-days is beneficial for an engineering team

Why estimating work in development always fails? Because I can only estimate things I have done before within a context that I know. The nature of software is the unknown, therefore any estimation will be unreliable. Using story points is the compromise the industry went for to account for that. Going back to time based isn’t helping anyone. Imagine being a navigator on the ship of Columbus - you only know the direction heading for but neither the goal nor the circumstances (riffs, streams, weather) ahead. And then the captain asks how long it takes to sail around a storm…