There certainly is a bit of an art to learning from textbooks on one reading.
Sounds more like magic to me. I've seen research quoted recently that indicated people retain only about 2% of a book after a month of reading it through once.
Edit: Further elaboration, prompted by the downvote:
How do you reinforce understanding of earlier material without referring back to it?
And if you do refer back to it, can it still be called one reading?
Plus, If you periodically expose yourself to the same information multiple times, it's not much different from using a SRS, though one could claim it's less efficient, especially in the long run.
The sentence I quoted seemed to be making a claim for eidetic memory, hence my skepticism.
Spaced repetition is one of the most efficient ways to learn new things. (For research citations, see 'Study methods', here.)
The best way to practice spaced repetition is to install Anki to your phone, since you have your phone with you all day long.
I have an Android phone, so here's my 60-second guide to getting started with Anki on Android: