I think Biggens means do you prefer them to make you wait outside while they drill, or for them to let you stay and watch it being done. Nothing to do with how good a ball driller is at taking existing specs and doing it up for you without you being there. Any ball driller should be able to do that quite easily.
It hasn't worried me over the years, however you have to remember that when you're drilling a ball up it requires some concentration, especially if the ball driller is trying something a bit different layout-wise. If the customer is talking to you it can be easy to make a mistake without realising it. If a ball driller does or doesn't make you wait outside, it shouldn't have any reflection on their ability, rather just what their personal preference is. At least you know they definately want to get the job done right the first time.
I don't mind people talking to me when I drill up balls, it's probably quicker to get it done if they don't, but I don't find it a problem. I've usually got the radio on anyway when I'm doing it on my own, so there's no real difference as such anyway.
Just my opinion,
Cheers,
Tim.