She can do several in a row, but keep them short, maybe 4-5 mins if she has a lot of metal in her mouth. After you do it for awhile your body lets you KNOW when it is time to spit, but this will help - I did short pulls the first couple weeks when I know I was the most toxic and did not experience any toxic overload.
Glad you found this place, it is amazing how many people outside of here I know have started doing this! Such a great, cheap way to detox. I am very thankful I found this place!