They’re looking into making the Bountiful rotation more sensible in the next patch. Let me find the note.
EDIT:
Bountiful Delve Rotation Changes
We’re changing the logic under the hood for which bountiful delves are active. Previously it was one delve per zone chosen as bountiful. This led to some behaviors where it felt like the same delve was bountiful back to back, especially in areas like Ringing Deeps where there were only two delves available. The new logic will rotate through delves from the original launch until all of them have had some time in the sun as bountiful before turning on new ones.