I like this analogy. But I was picturing myself asking my sales manager "How long would it take you to learn to play a song on piano?", and I'm pretty sure he would reply "but you touched a piano before, you are supposed to be a professional piano player ! A professional piano player surely knows how long it would take him to learn how to play a song". So I guess he would miss the point totally :/

Ironically missing that some folks will never be able to learn some songs.

And, learning to play an existing song doesn't necessarily translate to being able to write one.

Estimation is hard if you are stuck in the mindset that you have to make a point estimate.

It's not hard at all if you are willing to be (and are allowed to be) honest about the uncertainty of the inputs and calculate the uncertainty of the final result based on that.

It's true that people may demand precision that you can't give them. But at the same time, you know something and it is simple to compute what you know.

It's like Fermi estimation, that everyone hates so much and claims is so useless to interview for.

Even distributions can fail in execution. I can't remember the name, but the joke rule that work expands to fit the time given to it. Such that, if all work expands to the max of the distribution, your time is easily set at the point of the max.

Of course, this has been tried and doesn't work. The max time on many distributions is effectively infinity. Which, fails. For obvious reasons. And is why I assert you can really only talk of how long you are willing to work on something. Not how long it will take.

This!

If you estimate, estimate a distribution.