We just had an appt w/ our pulmonologist at Stanford. My daughter is 5 with CF, so I'm sure it might be different because she is a child.
He indicated that we need to do two 30 minute sessions per day when she doesn't have a cold. We are supposed to have the Frequency low, like 6, 7, and 8 for 5 minutes each with a pressure cranked all the way up to 10. In between each 5 minute session we are to do huff breaths.
Then for the last 15 minutes he wants us to have the frequency high, like 14, 15 and 16 and decrease the frequency to 6 or 7. with huff breaths every 5 minutes....
that's just what we do and seems to be the most definitive advice we have been given.