Close, but no cigar

 The woodpecker method is a carbon copy of the seven circles of madness.

We found out what works in the method and why, and what doesn't work and why not.

First time exposure

First of all, it works for everybody who has never emerged himself in tactics before. The first time exposure to tactics will get anyone 250 rating points, no matter the method. 

It becomes increasingly difficult to play in tournaments and to be NOT emerged in tactics. Because there is so much material on the internet available nowadays. I noticed that the tactical proficiency has risen, the past decades. Even new members at the club usually have a lot of tactics under the belt already. Only older guys with some clumsiness when it comes to computers tend to lag behind.

For MDLM, Tikkanen and Smith, the seven circles worked. For mere mortal people, like the Knights Errant, it didn't.

Understanding

The difference is, that you need to make sure you thoroughly understand a puzzle before you start to absorb and repeat it. The stress on speed, makes that people fail to do that and start too soon with the repetitions. MDLM said that the first 3 circles were for understanding the problem and the next 4 circles for ingraining them into your memory, if I remember well. Or maybe I made that one up.

And even the woodpecker method advises you to start with a limited amount of  problems in the first circle, as much as you can chew in four weeks.

Speed

Apparently, for the authors it was self-evident that you only start the circles when you thoroughly understand the problems, so they didn't feel the need to stress that. Furthermore, the emphasis on speed put the readers on the wrong foot.

There is certainly a role for speed, but it is far more subtle. Speed is a method of measurement. But during the training speed is taboo. During the training, speed frustrates the understanding and absorption of the knowledge, and it must be abandoned at all cost. Only after the seven circles you can use speed to measure whether you have absorbed all knowledge. Only what can be retrieved without effort and time is absorbed. Speed is a result of training. During the training, speed works counter-productive.

Why seven circles?

The amount of circles is arbitrary. You can do it with no repetitions at all, or with 30. Less repetitions means faster progress due to more focus and being more out of your comfort zone. It is a matter of preference, discipline and available time. In practice, I usually am closer to 30 repetitions, due to my laidback approach.

Spaced repetition

Spaced repetition is usually used for remembering the moves of the variations. That has nothing to do with absorption of knowledge. You must use spaced repetition for remembering the knowledge, the logical narrative, the standard scenarios. Remembering the variations is useless, because knowledge is position independent.

I am inclined to say about these methods: close, but no cigar!