Lets say I have a few pet peeve shots that bother me. Can I just learn cte/pro 1 for these shots or I must learn the whole system to encompass all shots? Is it all or nothing?
CTE/Pro One is a system. Is it possible to learn CTE/Pro One and then use it for certain shots, more difficult shots, etc.? Theoretically, it could be. But if you put in the time and effort to learn the system, I'm not sure why you'd want to. If you watch the DVD of Stan's 105 ball run, you'll see he isn't robotic about it in the least.
I may be mistaken but I suspect most players use some combination of aiming systems when they play. If you have a ball centered 3" from the pocket at a straight in or thick cut, do you need an aiming system? You're likely thinking about CB position but I seriously doubt you're applying an aiming system, at least I think most people wouldn't. In other words, I believe most players use a feel/experience system for a lot of shots and then apply their aiming system of choice for shots that don't fit into their automatic or "on cruise control" library.