Check out the Arrow Laser Aim and Laser Fire at http://www.arrowlasershot.com/
It does not use a computer to give you feed back if you hit the target. It can be used indoors, in any room that has a flat wall to project on.
The Laser Aim fits in the barrel and has a wire with a ring that goes on your finger, when you touch your finger (w/ring) to the trigger it lights up the laser. The Laser Fire projects a beam on the wall that represents a target in flight. You can set it up for most angles and speeds. It even has a feature that lets you set it up for voice command.
You set it for the shot you want to duplicate, turn it on and when the laser dot(target) moves across the wall, you mount like you normally do and when you touch the ring to the trigger and the laser fires you will see where you were in relation to the target.
About distance, different distances and speeds require different leads. If you visualize what the lead should look like in your mind for say 20 yd target, then when you mount and pull the trigger at that lead you visualized and the laser will show you if you were ahead, behind, etc. If yo visualize what it should look like for a fast 40 yd. target, then you mount to that lead and you will see where you were.
Flashlight drill only helps develop a smooth swing, using the Laser Fire and Laser aim
you practice mounting and placing the gun in front of the target which is what you do when firing at a target on a Sporting Clays Range. I know we are not supposed to measure leads, but I believe that your Sub-Consious sees the lead at the barrel and not at the distance it is from you. I found using my Laser Aim and Laser Fire that I was slowing down or stopping my swing.
For the heck of it, on a Skeet field which we know is 40 yd's from the high to the low house. So starting at the low house take 2 clays and set them 3 ft. apart at 20 yds(middle)
Then set 2 clays 6 ft. apart at 30 yds. and 2 clays 9 ft apart against the high house.(40 yd's) Then mount your gun and hold on one of the clays at 20 yds and see what the gap looks like to the other clay at 20 yds. Then do the same at the others and see how much difference there appears to be between the clays at the different distances. Try it, it will supprise you.