If you play well I'm sure you have some kind of pre shot routine to accomplish this with your feet, body angles, hand/cue alignment, etc. Then it's essential to see the cue ball and object ball connect in a way that creates the angle you are trying to "create" to make your next pool shot.
This can be done a variety of ways and you can call this a "system" or not, it's up to you. I can use several "aiming systems" if I choose to, however, the most important thing to me is to AIM WITH THE CUE BALL, instead of "AT" the object ball. Your distance from the cue ball you can control on a consistent basis, and this is impossible with the object ball.
Therefore, the specific "aiming" is easier done usine a specific part of the cue ball and a "relative" spot on the object ball. Whether you use the top, bottom or middle of the object ball I feel it's important to focus on the CENTER or EDGE (depending on how much "cut" you need) of the object ball to calculate your angle with.
I look at ALL shots like they're "staight in" first before letting my mind focus on what angle I need to "Create". When all is said and done pool is a creative game played with feel and touch, the eyes are used to establish the required information for each shot.
I've never heard a champion talk about winning a tournament or match because their "eyes were good that day." They will comment on how good their feel/touch was because that's the "difference that makes the difference." 'The Game is the Teacher'