Excavation Site 9 has been Bountiful three times in four days. Sidestreet Sluice has not been Bountiful in these four days.
I wonder if that is related to how the delves that actually provided bountiful rewards today also didn’t match the bountiful portal room. i.e. Waterworks was one of the portals, but it wasn’t bountiful when you actually got to it.