I'm glad to hear you're getting the results you are looking for. For anyone new to TOI, this is what happens when you start to incorporate this way of playing and pocketing balls:
Since ball pocketing is more about "feel" than anything visual the calibration to the CENTER POCKET is what creates the margin of error of the 3 Part Pocket System.
If you calibrate your shots to hit the center using the TOI Technique, this means you are unconsciously aligning to the part of the pocket closest to the object ball. This means if you are off on your TOI you will hit the first part of the pocket, if you hit it perfectly you hit the center and if you use too much TOI you will hit the outside of the pocket.
The positive "side effect" of using the TOI is "if you don't make the shot," you will know exactly why. If you undercut the shot, use more TOI and if you over-cut the shot use less TOI. Your speed may also be a factor, so if you undercut the shot, use more TOI Speed, and if you over-cut the shot, use less TOI Speed. I rarely see a student use too much speed, so if you're going to "error," do it by hitting the ball with more shot speed.
The trouble with trying to hit center{cue ball}and hit the center{pocket} is you don't have the "feel" of the 3 Part Pocket System, and if you miss you won't have the feedback of "why" the ball wasn't made.
After using the TOI for 3 hours straight you will experience the TOI "Pocket Zone". After a few days it will start to become second nature. 'The Game is the Teacher'
www.cjwiley.com