It depends on how they estimate and how familiar they are with the code base. I know developers that have been nearly spot on consistently with modifications an

It depends on how they estimate and how familiar they are with the code base. I know developers that have been nearly spot on consistently with modifications and maintenance work. The wildly inaccurate stuff seems to come from new work with loose definitions, manic developers, or situations where the work is billable hourly and outsourced. Sometimes it's good to have an old, graybeard developer on the team :).