This 7-20 sequence was revealed by Dr Clark at the same time as she revealed the zapper, on her book “The cure For All Cancers” (TCFAC), as a whole.
You will find a short description of her theory here https://www.curezone.org/clark/zapping.asp
“Generating positive offset frequencies is the best way to kill all pathogens quickly. But it takes more than one treatment.”
“It takes three treatments to kill everything. Why? The first zapping kills viruses, bacteria and parasites. But a few minutes later, bacteria and viruses (different ones) often recur. I conclude they had been infecting the parasites, and killing the parasites released them. The second zapping kills the released viruses and bacteria, but soon a few viruses appear again. They must have been infecting some of the last bacteria. After a third zapping I never find any viruses, bacteria or parasites, even hours later.”
The 7mn_On can be anything from 7mn and up. For some people, 1mn could be a good start.
The 20mn_Off can be anything from 20 to 45mn, but 20mn gives a more compact overall sequence.
I recommend this sequence when using the zapper for the first time, because it is not too “hard” on elimination side effects.
Straight zapping is very convenient, and I use-it very often, but the “interval zapping” is a very good way to zap and has a VERY good record. Good to know. Good to try.