On a prepcheck run each reading item (SF, F, LF, BD) from the assessed list of items on the prepcheck buttons.
Theoretically, each button can be run to F/N. In practice, one would not continue to run the buttons beyond EP for the subject being run. This EP would be signalled by a major cog or regained ability with a wide F/N and VGIs and the charge on that button blown.
Each button in turn is run to F/N, Cog until the full EP is attained. This may require running all the buttons in some instances.
One then takes up and handles the next best reading item from the assessed list and continues until each reading item is handled.
The LRH datum (per HCOB 8 April 70) remains valid. The handling of an ARC Break to F/N on one of the buttons would end off that prepcheck button. One may run further buttons if the major cog with wide F/N is not attained.
Get the most out of prepchecks by running them to full EP with all charge blown.