I would generate random practice text with computer programs that would slowly increase the code speed from 5 to 15 words per minute over 90 minutes, the duration of a standard cassette tape.
I first wrote this for a DEC PDP-11 laboratory controller that happened to have analog inputs and outputs. I made random length words up to five characters long.
My wife to be practiced copying from tape as we drove across country heading to Oregon. A ham we met on-air in SF pointed out that it was exam day at the FCC. Karen gave it a try and passed her 13 word per minute code test for a General class license.
I wrote the program again for the Magnolia Workstation using the sparsely documented audio chip that had been tossed into the design. This time I wrote random syllables alternating vowel and consonant so that there would be more shorter letters in the text.
Dave Keith achieved proficiency for an upper grade ham licence with the Magnolia generated tapes.