| Slight tangent: I once worked with a programmer who, the vast majority of time, would only input text into a text editor via copy and paste. Think anti-vim. His fingers were locked on mouse and crtl+c/v. It was incredible to watch and his programming speed was very impressive. |
In the case where you are copy-pasting out of code you don't really understand. Retyping it gives you time to understand and maybe catch existing bugs in the code you are copying.