This is a sample position from a book (no further details are given to avoid copyright issues).
I can read the first line and follow it in my mind, departing from the figure. But the continuation in the 2nd and 3rd line is too much. I cannot look at the figure and remember what pieces are supposed to be in different squares, much less do it in a proficient way (i.e. I might place a non-existing bishop in a square in my mind, but not realizing which other squares he is threatening).
However the book is not for advanced players. I wonder how are readers supposed to follow these comments and variations, if you are supposed to use a physical board with pieces, or if you are supposed to visualize all that in your mind and the problem is that I need more practice on that.