Thanks, holtju2. I've been trying to find if it's already up, but you're it.
A couple of quick tests turned over a couple of rocks: T&C say all flights must be on United metal. But, for example, IAD-MAD is on Aer Lingus, and it's in on the sale (and for which I was seeing "46,500" miles -- 22% off). And I don't find anything by UA to southern Africa - even bookable at all - so it appears to be out. So I wonder if they're overstating the geography of the sale. Also, for the itineraries I hunted on, Tuesdays and Wednesdays are scarce.