Long ago, at a company that has since been purchased twice, one of the project engineers was famous for writing up his estimates for the exact amount, with no padding. On more that one occasion, somebody in the finance office would automatically cut 20% off, then someone else would yell at him for going over the budget. His response was usually something to the effect of "I told you how much time and money was needed; this guy changed my estimate. I know what I'm doing, and I don't put in padding just so it can be cut so some bean counter can look like he's doing a real job."
This only worked because the person who did the cutting was not the same person as the one yelling about going over budget ;)