Does anyone else on HN practice the multiply by 3 formula for estimates? I don't recall where I've come across it online first, but it has worked very reliably for me in the last 3+ years.
My team wants to know the mean; my manager needs to know where the cumulative distribution reaches 90%; and marketing needs to know where the cumulative distribution reaches 99%.
In my experience, a developer's educated guess hits very close to the median completion time. Software task completion tends to be lognormally distributed, so to get the appropriate scaling factors, multiply that educated guess by 1.6, 5, or 10 respectively.
But yes, I subscribe to the approach of make your best guess, then multiply by 4.