Agreed. I'm much less liberal with my estimates with external stakeholders than I am with close associates, purely for political reasons. If I say 8 weeks to my team, I'll say 11 to management/others. I get no benefit out of delivering on time, a little for delivery early, and a massive loss by delivering late, so I have 0 incentive to give them an "early" estimate. Under promise and over delivery is corporate strategy 101.
