The whole process of analysing a tactical position can be divided in 3:
The reasoning, seeing the moves, visualize the steppingstones.
Today I tried to visualize the whole tree with 25 branches and 125 moves from the position of Kotov's book. I was pleasantly surprised that that was fairly easy. The start was somewhat difficult, but I began to feel stronger and stronger while progressing. After a few hours it wasn't a problem to reconstruct the whole tree complete with my eyes closed. So this makes it quite clear that the reasoning is the weakest link by far.
I intend to exercise all 3 techniques apart. Since I'm so bad in reasoning, I intend to make use of ROS (TM) Reasoning Out Loud in stead of inner speech. Further I allow myself to move the pieces by hand to make it easier so I can concentrate on reasoning. After I solve all elements of the position and after checking it against the solution and the computer, I will close my eyes and visualise the whole tree. I really look forward to it.
The poor image that is procuded by the physical eye is enhanced by the brains to a beautiful picture. It's a pity that we can't use that brainpart to enhance our poor image which we create during visualisation with the mind's eye.