I never went, but thought I was going to get assigned once.
I had been sec checked and interviewed once a week for 5 months straight because I kept pointing out outpoints, cross ordering RTC, and other things to prevent ultimate brainwashing, so at that moment they had me convinced that all the problems were in my head and the RPF maybe wouldn't be so bad. Luckily I was connected to Jenna at the time and they had different plans for us.
But regarding the statistics for it, it really depended on the lines you were on. When I was posted in Snr HCO Int, IJC showed me a CBO (Management Policy) where Elron says the fastest way to the RPF is either via Programs Bureaux or the HU (Household Unit [LRH's personal staff]) because of the lines you were on. And boy, did it still get used as mostly people from FB and anyone sneezing wrong around COB went.
When I was at CCInt though, people only went with out-2D or had a supposed R/S and the only real threats made were towards the celeb auditors.
But then again, later it was a major flap that there were more than 150 RPFers in PAC so they started posting people as Dishwashing and Dumpster I/Cs, where before they would have gone to the RPF.
So I guess it depended on what color the hair on Dave's gerbil was that week.