I've spent a fair amount of time fiddling with the lettering on various motivational-poster parodies and remixes in the LOLErf thread. I'm pretty sure that Rob's standards for an acceptable final comic page are tougher than mine for a relatively minor gag piece.
I can believe that it takes quite a bit of time to work out issues like adjusting character spacing and size to produce good-looking and readable dialog boxes while blocking out as little of the artwork as possible.