I can definitely relate to this.
DFM checking is important, but for prototype boards there should be a balance between catching real manufacturing issues and creating unnecessary back-and-forth discussions.
For example, if a board intentionally has no silkscreen, no bottom copper, or uses unusual outlines for mechanical evaluation, experienced CAM engineers can usually identify that very quickly and proceed without generating multiple clarification loops.
In our factory, we try to focus on issues that may affect manufacturability, reliability, or yield. For intentional design choices, especially on prototype builds, we prefer a "confirm once and move forward" approach rather than repeatedly questioning every non-standard feature.
Many RF, microwave, and prototype customers send us unusual stackups, cavity boards, mixed-via structures, or mechanical evaluation samples. Fast engineering review is often just as important as fast manufacturing.
Out of curiosity, how much delay does the clarification process usually add to your orders?