In my experience, the results of NAP workings have occurred so rapidly that I have caused my own 'backfire' by not being ready to take full advantage of the result and have missed out on some opportunities presented to me on the proverbial silver platter. You live and learn. Now, when I have such an opportunity, I work as hard as I can to utilize and honor the gift.
The results can be most unexpected as well -- immediately after finishing the last word in one particular working, a ball of energy, literally flew out the inside of my head exiting out of my left eye at high velocity. It was not painful but it was surprising and left me wondering what had happened. There is no way to define this sort of thing that I know of. I forgot about it and then a week later while sitting in my car in traffic, I reflected on the experience and wondered about it -- at that moment I saw the 'ball' again, in color it was swirled black and white and it was spinning in place high above me. I could see it through my left eye, say at 11 o'clock (on a clockface) somewhat high up in the air, it seemed like it was hovering over me.
You live and learn. I still have no answer for that was all about, but am left knowing that the unexpected can happen.