To me the holes in the ribs look big enough, unless they are smaller than the cable diameter.
The holes in the Venture 60 rib are smaller than the size of a standard Futaba J connector, so if you're using those you need to enlarge the holes a bit.
I don't understand why people always drill huge holes and install wire tunnel tubes.
Neatness, and being able to replace the servo/extension without having to cut and solder I suppose.