Do you focus on the front, middle, or back of the rim?
My teaching methods are a bit “out of the box” (non-traditional) and not everyone takes to it. I will answer you questions the best that i can, relating to the methods that have been successful more me but I don’t know if they are the answers you are looking for.
I do not teach target. I believe that shooting is a kinesthetic skill, not a visual one. I believe you shoot by feel, not by sight. I often teach players to shoot with their eyes closed. I want them to concentrate on form and feel, not whether it goes in or not. Given enough repetitions, they learn to adjust their feel for distance. I can routinely make 80% from the foul line with my eyes closed. That is based on that the monstrous amount of repetitions I have had in my life. I don’t expect young players to do that but it serves as a good illustration. Pro players routinely shoot for a higher percentage than I do. The direction of flight is determined by your follow through. Just follow through straight at the rim. To be more traditional, why not aim for the hole? Isn’t that where you want the ball to go?
Where is the guide hand placed exactly? Do the fingers and the thumb point up in the air or to the rim when holding the ball/releasing?
When I teach shooting early in the process, I teach it 1 handed with no guide hand. Once we add the guide hand, I usually stress comfort. As long as the ball is steady and and your guide hand doesn’t interfere with the ball and shooting mechanism, you can place it however it is comfortable for you, as long as it is the same every time.