Well, with the ES-3 you've only got two pots and the distance between them isn't large. So you've either got one short length of wire or a capacitor joining the volume to the tone pot. The connecting ground wire doesn't need to be shielded. Whilst you could use screened wire, for very short lengths of say 5cm/2", I wouldn't bother. You'll need to have a certain length of the wire exposed anyway at either end to prevent shorting the signal, so you'll end up with close to the same length of exposed signal wire even if you did use screened cable.

The output jack wire will be longer, so is worth using screened wire for. The longer the wire length, the more important it is that it's screened if its not in a shielded cavity.

Once you move on to two pickups and switches, then I'd use braided screened wire where possible and generally follow the method shown here.



Using heat shrink or insulated sleeving over the braid in proximity to pots or switches is very important to avoid the possibility of signal shorts to ground. I suffered from this just the other day when I found that the tone control on my open-G 5-string Vintage V130 LP special DC-style that I'd rewired didn't work, because the braid of the output lead was being pushed against a lug of the tone pot. Now fixed.