On the rare occasion I can get him to slow down ever-so-slightly, his quality and accuracy go through the roof. I just haven't figured out a way to get him to hit the brakes.
Have him imagine that one day he will design an airplane or a giant skyscraper. What would happen if he makes an error in his calculations or assumptions?
We will have this conversation tonight.
Nearly every mistake so far this year (only 3 weeks, but lots of work) has been due to carelessness. Frustrating.
I told him that while we do not expect perfection, we expect him to at least take his time and show that he cares about the quality of his work.