Depends on the situation.
For instance, in the case of both of these comics I did all the rough sketching in a light green and then "inked" it, all while never leaving the computer.
But sometimes I want a better level of control over how my art comes out, and I do a lot steadier sketching in pencil than with a tablet, and in those cases I do pencil sketch -> scan -> digital ink.
I dunno, depends on the drawing and how much time I want to spend on it.
