The use of margin of error here is not the industry standard.
Well, I didn't start using it, Duckie, I think Dr. Dave did in his book (great book, not knocking it at all). It is actually a statistical term that has to do with the probability of the prediction of an event being true. It is more relevant to the type of random scatter that might be predicted if one is trying for the exact center of the CB. It has nothing at all to do with pocketing geometry, no matter how much Pat wants that to be true.
Excuse me now because I'm gonna reach here a bit and compare the "margin of error" involved in trying to hit the ball just to the inside of center to that involved in playing a stringed musical instrument in tune.
Probably half the membership here has at least tried to strum a guitar at some point in there lives. If not, it's likely that you at least know it has metal bars across it called "frets", and that these bars are exactly one half step apart on the musical scale. Place your finger just behind the fret and the correct note sound out, perfectly in tune.
Now pick up a violin. It has no frets to place your finger behind. If you place your finger in the precise position, the note is in tune and sounds OK. If you fall a little short, the note will be flat and sound like shit. Reach too far up the fingerboard and it will be sharp and sound terrible as well. So how do you get it right on the money every single time like a professional player must?
Every first-rate player I have ever talked to (and I've been in the business for a very long time) "aims" just to the short (flat) side of perfect. Call it a "touch of inside" if you will. If they hit it just right, they immediately add vibrato to swell the sound intensity. If they hit it a little flat, they immediately vibrate the finger up into tune and it sounds good. If they note is even flatter they do the same thing, but you may hear a very slight slide up to pitch. If done correctly you will never notice it in the music. Call it a "three-zone note pocketing" system".
An interesting thing happens after some time practicing this technique. The real flat notes start to be fewer and farther between, while most of the notes fall ever so slightly flat and are corrected the same way so they all sound good. The rest of the time the finger land smack dab on the correct spot, which still "pockets" the note.
Never does a good player land sharp of the proper spot after playing for several years. By "aiming low" they effectively eliminate the high side from their playing, and spend 99% of their time either hitting the note ever so slightly flat or hitting it spot on. Their mind eventually learns to avoid the sharp side entirely, and thus, increases the probability that they will land acceptably correct on the note.
Pretty cool Jedi mind trick, eh?