Also, assuming that I'm understanding it right, you really won't be able to focus your efforts on maximizing your odds for a specific type of small prize. You have a 1:16, 1:15, 1:14, etc chance at all the small prizes, until you hit the reshuffle, where you're back at 1:16 again.
Something they haven't stated yet is what the distribution of small prizes will be. Will there only be 1 out of 16 that is a building (I'll guess yes)? Will that building be consistent for 24 hours, even after reshuffles (I'll guess yes) or will it change with each reshuffle? Will the other small prizes stay consistent throughout the entire event (I'll guess yes), or will they stay fixed each 24 hours, or change with each reshuffle?
It will take a little probability musing to consider the relative odds for a daily buildings in the long run with this system versus the old. This system, you have small (6.25%) but increasing odds until you get it, followed by zero chance until you reshuffle, at which point you're back to small but increasing odds again (plus, a possibility of getting double payout). Past system, you had 5-30% chance each go, depending on which orbs presented itself. I don't know if it's already been worked out; If not, I don't know if I'll give it a whack.
Bottom line, though, if my guesses are correct, you should still be able to save up your ribbons to binge a lot of presents so as to get a particular daily prize building in quantity, but should also get a more varied selection side-effect prizes.