How to flash cards with the 50 picture set

This is taken from a posting by FrukeC
When my son was about 2 years old, I contemplated quitting Shichida classes. He had been in the program since 3 months old and we weren’t seeing results. He wasn’t even interested in 6 LM pictures but at 2yrs 3 mths, something miraculous happened. He could name all 50 pictures in Linking Memory Set 4 in the correct order without looking at the them. He went on to recite 150 pictures in LM Sets 4, 5 & 6 continuously 2 months later. That renewed my confidence in the system and thus I spent more time creating home practice materials.

I am still not sure how to proceed with this exercise
The example given in Shichida book, is as follows:

One day a dog put on a hat, and went on board the ship eating a strawberry with a fork, on top of which was a butterfly…

As you recite the story, you flash the cards with the pictures.

What is the miracle that happens by the time you get to 30 cards ???