In Science Fiction, there's really only two types of engineers that matter - embodied by Montgomery Scott and Geordie La Forge, respectively. (Sure, there's Kaylee from Firefly, R2D2 is good in a fix ... but you'll see where I'm going in a second).
You either get stuff done, or you don't. Anyone who doesn't get stuff done simply should not be calling themselves an engineer. And of those who do, you have the ones who say "It'll take a week" and then do it in an hour (the Scotty approach) and those who say "It'll take a week" and it takes a week (The La Forges).
While I have great respect for the Scot, that's simply not how I roll - padding my estimates leads to a scenario where all estimates are simply ignored, because everyone knows they are padded.
Which leaves me in the current situation, where nearly every estimate I give appears to be met with incredulity and ridicule - even when they are repeatedly borne out, as any later analysis can demonstrate.
So - how do you, as an engineer, handle your estimates? And when you give an estimate, and someone argues with the numbers - how do you approach that conversation?