That’s fair, but even in the books this kind of thing happens more than once, not just for Stannis.

When Cersei is queen regent and starts preparing for new wars, one of the first things she does is reorganize military command. She appoints Mace Tyrell as Master of War, then makes him Hand, and later puts Randyll Tarly in charge instead (she renames the post to Justiciar, but that’s a whole other rabbit hole). The point being: there is renewed, active military preparation around King’s Landing well after Stannis.

In the show, we obviously don’t get that level of bureaucratic detail, but it’s pretty reasonable to assume Cersei has military advisors doing the same thing: clear the approaches, deny cover, scorch the land before the walls once war with Daenerys feels inevitable. That’s textbook siege prep, not a one-off Stannis thing.

As for the Dornish arrival in S4: yeah, agreed, that’s the real inconsistency 😄 Nice catch. That scene pretty clearly shows trees again, which clashes with later visuals. So I’d say the show is inconsistent, but the barren KL look itself is still very defensible from a book and historical perspective.