Every chapter's pref ceremony is not the same. Nor should it be.
The ceremony should be unique to your chapter in that it matches the needs of your chapter, the environment of your greek system, and the PNMs going through recruitment.
As has been said, pref isn't ritual, it's pretty openly discussed, at convention, online, during OVs, etc. If it wasn't, my chapter's pref ceremony would continue to NOT work for us like it did for several years before we got help. I don't know Ivory's opinion on this (my co-mod for this forum), but I have no problems at all with sharing these ideas on here. If you really truly have an issue about it, please PM myself or Ivory.
Plus so what if a PNM sees some ideas about what pref may be like? The execution counts more