I think anytime you have an actual point to focus on rather than trying to send a spherical object into a precise space, you will have an easier time hitting the target. For example, I can send the CB up to the center diamond on the end rail and have it split the CB down the middle, even using side spin. I can easily see when I am off as well. When I try to send the CB into the GB position, I clearly know where I want it to go, but it is often much harder to get it there. I will miss many shots trying that way.
What I do instead of classic GB is to align to the shot line that the GB provides for me, but as I bend down to the shot I forget about everything except for the precise point on the OB that the center of the cue was pointing to when I took my stance. This gives me something objective to shoot at. Not the contact point, but the spot on the OB that a straight line through the cue is pointing to as I go down on the shot. I take whatever clues I can get along the vertical axis of the OB (a stripe, a number, light reflection, etc., or sometimes a spot on a rail or a spot in the room on shots greater than 1/2 ball hit) to remember the right spot to aim at, and then stroke straight at that spot and the ball (usually) goes in. I think this method was described to me as "back of the ball" aiming, where you find a particular spot on the OB that you can shoot directly at to make the ball.
That said, I have seen this shaft aiming method on YT before and have played around with it a lot. This method has a lot to offer to guys who see and shoot like I do. Instead of trying to aim at an imaginary ball, or a spot on the back of the ball that is a construction of my own mind, I can aim one side or the other of the shaft directly at the contact point. That's about as objective as you can get. It works for a remarkable number of shots, not just a few select ones. I find it particularly deadly for long back cuts, or cuts along the rail. Gets me by the optical illusions that such shots always create for me.
I can't say how well it works for side spin as I don't ordinarily use much side at all, but for cinching many shots it's a real handy technique to know IMO. I have been very successful using it, and the hardest part for me is to avoid losing the exact location of the contact point as I move into alignment. When I dial it in correctly I get a much better contact with the CB as I feel like I am shooting directly into the OB ball instead of through the CB. I think this feeling alone makes the method worth pursuing as it makes me more confident in my stroke, giving me a more relaxed power and a straighter stroke.