I can do most DIY jobs. I can do wiring, plumbing, decorating (including pattern matched wallpapering), fitting shelving or other things to walls, and I do it well.
What I can't do, is hang doors. I don't know why, but I suck at it. Maybe it's because this 1930s house has never had a standard sized door, never mind once that's square.
The only way I can hang a door and do a good job, is if I'm fitting the frame as well.