Finally made it to 5 brands (HR, GH, Centric, Thompson, and Unbound), and my certificate deposited immediately after my stay posted (expiration set for one year out).
I have stays set for Park Hyatt and JDV soon, so I can probably get to 10 pretty easily if I can squeeze in a Hyatt House and Hyatt Place stay, along with either a Destination or Hyatt stay. Of course, I'm not in a rush to make it to 10, and it seems unlikely that I'll make it to 15 anytime soon (I don't foresee any Urcove, Miraval, Ziva, or Zilara stays in my future anytime soon :-)).