I think it's a pattern of planetary hours that is based on Rulerships and Exaltations. The pattern goes like this (vertically)
Mercury (and so on and so forth...)
If I take the Minchiate Zodiac cards, line up the cards in a table with the Lilly pattern, and then label the table with the corresponding Rulerships, Exaltations, Detriments, and Falls, a pattern clearly emerges.
The card sequence is in retrograde: