It happens. Shit hits the fan. And Shit flows downhill. At some point it needs to land somewhere.
Where it lands depends on a few things. If its an easy finger pointer, ie, the Art Department Assistant sent the wrong file, its easy. The Art Deoartment Assistant will wear a few; its to be expected.
When theres a problem with the build the plot thickens. There are going to be several factors, several departments involved and chances are, each one affected the other, and no one knows the whole picture. Shit starts to slide.
The Production Designer hires people to do the job. Its not the PD's fault, nor is it their responsibility: Thats where the Art Director comes in. This is where the Art Director gets a personality test, and this is why the position of Art Director is so hard. Its the Art Director's responsibility, therefore, the shit must fall on the Art Director. Even if the Art Director diddn't do it; the Art Director's job is to oversee the production of the Set Design. How the Art Director handles this shit is the personality test.
A lousy Art Director goes directly to blame the person they can find at fault. They are missing the point of their job.
A good Art Director wears the shit boldly. Lets it stop there. Then, they find out what happened within their department, or the department involved, and takes steps to prevent any more wildfires, and of course, there are plenty more, just around the corner.
Art Director is a tough gig.