Thick or thin cut I aim directly at the contact point whether I’m using side or not. I know other players who swear by ghost ball, cte, track system .. whatever but your brain is making corrections for you most of the time. Case in point ..
We took a ruler at the hall years ago. Setup a shot about 7 feet from CB and ask the player to pinpoint the center of the ghost ball as I stepped away from object ball with a ruler held vertically. They said stop when they thought ruler was at center of ghost ball. We then measured distance and all the measurements were different, one player marked at 1 5/8 inches if I remember correctly. The weird thing is that each player made the shot with no problem.
It’s a reference point and after much practice your brain will make the corrections until you ‘feel’ it’s right. After many years the same has happened to me and although I know it’s not possible to aim directly at the contact point due to the “relationship of the spheres” it works perfectly for me. I don’t even see the balls as round, don’t care, I see the contact point clearly, better when I was younger, and the ball goes in the hole. I’d aim the same way if the balls were square