Manager: We (meaning you) need to do task A. How long will it take?
Me: Task A will take X days to do.
Manager: That seems awful long.
Me: How long do you think it should take?
Manager: It surely could not take any longer than Y days.
Me: Ok, it seems you have an answer to your question then.
Later:
Manager: It’s been Y days, why isn’t task A done yet?
I don’t work in programming (helicopter maintenance/repair), but my boss goes one step further.
Boss: How long until it’s ready for a test flight?
Me: I’d say…
Boss: Wait. Give me an honest number, don’t add buffer time. I’m already going to double whatever you say to tell District.
Me: Oh, okay, with paperwork and ops checks, 3 hours is feasible, as long as we don’t encounter any other issues.
Boss: roger, six hours, sounds good.