My inner munchkin is calling and he's hard to ignore. Which probably means I should stick to RoP: I...
I did try to search, but "Ceremony" is rather generic and I can't find a good combo to hit what I need.
I can't see that Ceremony adds any time to the performance of an ability? I mean it would make sense that ceremony use ceremonial casting, but it's not explicitly stated, and the time needed for ceremonial casting is measured in magnitudes, and while that would work for methods and powers, ceremony works for any divine supernatural ability, and not all of those fall out neatly into magnitudes of power.
It explicitly says a group of any size can be a disorganized group. Does this include a "group" of one?
I could justify one or the other, but justifying both reeks of broken, since it means you get a Ceremony -1 bonus on all divine powers at no cost, and depending on how you read the paragraph about benefits of the ceremony, you may get to double your stat+ability? No. I'm wrong. I'm being willfully blind to something obvious because I have no control over my munchkin tendencies.
Ceremony isn't described as adding additional time, but then its never been firmly established how long Invocation and Purity effects take under normal circumstances either. I don't really think adding extra time to Ceremonies is necessary, but if it fits your aesthetic better, it shouldn't hurt either.
None of the versions of Ceremony explicitly prohibit a group of a single person, but all do state that "You must gather a group together..." which could be taken as requiring at least two people. shrugs