Is it left vs right english, or "inside" vs "outside"? There's a difference.
Most players have more trouble pocketing balls with "inside" english, rather than "outside". Maybe it's because the inside looks and feels unnatural. I mean, when cutting the ball to the right, applying right english looks and feels a bit odd. Same goes with applying left english when cutting the ball to the left.
Using outside english (left spin with a cut shot to the right, or right spin with a cut to the left), looks and feels more natural, more normal. If it looks and feels normal, then our aiming compensation looks and feels more normal.
The good news is this: There is a certain range of stroke speed that will allow you to use inside or outside spin more consistently, meaning your aiming compensations will be easier to judge and apply, regardless of left or right or inside or outside english. That magical range falls under medium speed.
Dr. Dave has some great info on cb squirt and swerve, the two things that happen when applying side spin. Example: A cut shot to the right with inside (right) spin causes the cb to squirt off-line to the left, but then it will begin to swerve back to the right. The goal is to ensure that the combination of squirt and swerve results in the cb pocketing the ob. This is where aiming compensation comes in, which is another way of saying "guesswork".
A soft stroke speed causes more swerve to occur before the cb hits the ob, so we have to compensate quite a bit for that when aiming the shot. A firm stroke speed will cause the cb to squirt too far off-line for the swerve to have a chance to correct the cb's path, and so we have to compensate for that. But with a little table time you can experiment with stroke speed and english to find the speed that basically cancels out the squirt and swerve factors.
Of course, sometimes you'll have to use english with a soft stroke, and other times with a firm stroke. So knowing how to compensate for that is important. But figuring out the range of speed where very little to no compensation is needed, well, that's the nuts.
Thousands of players have switched to a LD carbon fiber shaft for that very reason, because the shaft reduces squirt so much that it widens the speed range/window where very little to no aiming compensation is needed.