Well if it works for you have fun with it.
Personally I see no value to such a device because it does not provide any feedback. That absence of feedback will reinforce a false sense of achievement because it only provides you with an aiming point, and no evidence of the quality of your shot. You don't know if you pulled a shot or if cant caused you to throw the shot off to the side. At such a close distance the angular error is hard to see making it even more difficult to evaluate your performance.
If you want feedback there is no substitute for actual shooting. You would be far better off with a high quality PCP air rifle and shoot that in the basement. That will provide real feedback. If you pull the shot you will see it. If you cant the rifle you will see it. A Weirauch HW100 with a solid steel barrel is surely more expensive than a DFAT, but far more beneficial as a learning tool. With good pellets you can shoot groups around 0.020" or better from 10 yards. If the quality of your shot is not perfect, the evidence will be clear on the target.
I agree with you,
if you want feedback there is no substitute for actual shooting, but not always people have the opportunity to go to the shooting range.
I use the IDTS in this way, TRIGGERCAM 2.1 to record my training session.and Mantis X to track my reticle movement on the targets.
If you take a look at this video you can see some correlations between reticle position on target when I broke the shot and reticle movement with Mantis X.
what I‘ve checked from dry fire and live fire experience is the following, if you have a score less than 98 probably you miss the target, or may be you have an impact for a lucky bad wind call, talking about real shooting to targets beyond 500 meters.
the inner circle of the Mantis X has a radius of 3.75 MOA, if you have a 98 score, you are very close to a deviation of 1 MOA, shooting to a 2 MOA targets if you are lucky you are on the edge.
Using IDTS I do practice with different COF, type of barricade ecc ecc, I works to build solid position, magazines change practice and much more.
I do dry fire using IDTS and some time with real targets looking outside my house, the most of time with the same configuration TRIGGERCAM and Mantis X.
Yes, I say again no substitute for real shooting, but with my approach I‘ve some sort of feedback
I did the training of this video using standing position with rifle on a QDT tripod and a bag.
I do also shooting with a PCP to 25 meters, what I think, do something is better than do nothing.