Ballstriker,
You bring up a concern that I hear over and over again. A justified concern to be sure.
Like anything else that we learn and need to apply there will be a change in proficiency and speed as skill and experience are gained.
I liken it very similar to learning to drive. At the beginning, I think there is a desire by most to practice the skills in a controlled environment like a parking lot or other similar place.
Eventually, a comfort in the skills allows for the challenge of the real road. Surely, one can look back and remember awareness of the surroundings a little lacking as a focus on the acts required to turn the wheel and hit the correct pedals is the main focus. Situations arise that you've never before encountered and choices are made rightly or wrongly. Hopefully, things are learned based on those outcomes.
Later on, real proficiency becomes a reality. You start to see potential accidents way before they may happen and your ability to embrace the environment significantly outweighs the focus needed to do the actions.
AimPoint is exactly the same thing. Information is learned and must be assimilated.
Practice needs to take place in that controlled environment. (the putting green)
Learned skills get applied in the real world. Situations are seen and choices are made.
Learning and adjustments are made.
Skill becomes proficient.
Speed becomes very quick.
On the other hand, there is no question that the accuracy of the read can increase with a little extra time. Either before from proper and accurate mapping or during the round when dealing with longer putts or trickier shapes.
It doesn't require a high level of playing ability to do it well though.
I've been doing it coming up on three years, and like Erik said I can get most of the read done before I've ever reached the green even on a course I've never seen before.
Granted, I have worked very hard to learn how to do it and to do it quickly.
Also, don't think that AimPoint should be used to completely remove all previous feel and experience. There will be times that whatever experiences you've encountered in the past will be relevant to the present. AimPoint enhances feel. It doesn't replace feel.
If you want to make putts and read greens fast, than practice it.
You can do both.