Yeah, you found GMS in English. Matryoshka (Russian doll).
This method is used to memorise figurative codes, for example, this way you can memorise 00-99, cards, other in 1-2 hours.
It is also possible to 000-999 to speed up significantly. 4-7 days for reflex connections of one hundred and save up, save up. The main thing is to have good images.
It is not used for training. In training you take one object, divide it into sectors, fill each sector with 5 objects (a bundle) and on each object allocate 10-12+ details, for each such object you can remember 10-15 images, and to them also clarifying images.