Sorry to dispel your myth about the "best chess training book" but the real problem is that the author, like his friends, didn't really improve of 400 points in a year. Check their statistics with the FIDE site, and you will realize that IM Smith just improved 35 points a year, over a period of 10 years.
The part of the book anyone strangely miss, is the endless hours with one of the best strategic GM, Ulf Andersson, who gave him and others endless hours of explanation, using his games. How many amateurs have a GM at Karpov level explaining his games? How much did they pay for Andersson?
And speaking of the "woodpecker" method, the guy mentioned as example to learn from, was making 1000 tactical positions a day (not 100, but if you go on chess tempo you will be able to select a set of tactical exercises like in the woodpecker method), and that gave him 100 elo points improvement. I don't think that is all the story, partly because at GM level the opening repertoire is very important. Secondly, because I don't know how many amateurs have the time to do 1000 tactic positions a day.
But if that was true, then what is the difference with De lamaza? It is the same identical idea. But strangely everyone attack De lamaza, but they worship this guy. It doesn't make sense.
The objective reality is that Mr. Smith, like his GMs colleagues, trained over an extended period of time, 10 years or more, played over an extended period of time, reviewed games, paid coaches like Andersson, read hundred of chess books, and then they achieved IM/GM status.
But the evidence he provides in the book is at the best anecdotal, not showing a method applicable to everyone which will sistematically improve 100 or more players over 1-2 years.
From the excellent book "Pump up your rating" by Axel Smith, Quality Chess 2013, Chapter 6 - The Woodpecker Method, p. 226: "For many months, I started every day with 45 minutes on chess.com, one of the Tactical Trainers that´s available on the net.
These programs comply with most of the requirements above: you have to choose a move, there is a clock with a limited time, you have to find all the moves to the end, your performance is measured with a rating, no exercise is impossible, and the webside doesn´t chat with you. ...
However, there is one big difference to the Woodpecker´s Method: the same exercises are not solved again".
I (chess.com user "Schoenbrunn") see this as a problem too. It should be possible to let chess.com select e.g. 100 exercises for me and i´m able to solve this 100 exercises again and again and again like a "Woodpecker" getting for this 100 exercises a "Woodpecker rating".
Pump up your rating is perhaps the best chess training book on the market and being chess.com the best tool for the Woodpecker Method on the net would be great for the chess.com-users and for the chess.com-company.
Best wishes