Board and batten window detail

I'm preparing to do my first Board and Batten DIY siding project. I've been looking at images on the internet, particularly looking at how windows are detailed. The picture I've attached here shows what I'm finding all over the place. The board and batten runs up tight against the the horizontal trim above the window. Same with horizontal trim dividing the first and second floor. Am I crazy or is this just asking for trouble? Shouldn't there be Z flashing to prevent rain from running down the boards and stopping at the trim, where it will sit and penetrate behind the trim (when the caulk eventually fails)? I've put arrows at these points of failures.

I've not seen a single board and batten picture showing flashing at these joints. Wondering if I'm imagining these points of failure.