Yeah, the plethora of people who say they are >1800 USCF with low blitz ratings...
Blitz rating is not all that important. I know a 1600 USCF player who is pretty much even with me in blitz (he's 1900blitz on chess.com, somehow I manage to play even with him OTB, probably because I care more about OTB games than online games) & there are NM's on chess.com with blitz ratings in the 1700's.
Yeah, but 9 out of 10 NMs will be >2000 in blitz.
But I realize it's not the same. Some people almost never play blitz, or when they do it's not seriously.
It's just people tend to exaggerate, and if your blitz is 200-300 below most of those you claim as peers it makes me wonder. I'm a skeptical person.
de la Maza is reinventing the wheel and advertizing it as the latest miracle cure.
What de la Maza gets right is that tactics are important and that it takes hard work to get good at it. What he gets wrong is his constant self-advertising, even within the pages of the book! He repeatedly tells you to follow his method and you will become an expert or a master.
How many people have actually become an expert or master following his method? I think the count is currently 0. Yep, even he didn't follow his own method because he himself studied openings, endgames and complete GM games as he admits.
But again, the idea of drilling tactics is quite old, and one that has been recommended by the Soviet chess school. Korchnoi and Botvinnik have both talked about practicing with hundreds of 2-3 move puzzles. Yusupov has said that 2-move checkmate puzzles are excellent for improving pattern recognition and tactical vision!
So, de la Maza has reinvented the wheel. That's not a problem. We should celebrate the wheel. But his book is about a wheel covered in snake oil.