I used Mix-Shader nodes to blend my 7 masked "materials" previously, and since I had to ( just in case) *not* do that, I was worried about the absolute spaghetti this would lead to, until I discovered "Bundle nodes" - crisis averted! It should be faster too, maybe? I don''t really notice it.

1st! I was hoping to post something more interesting - but my custom material blending setup needs a big overhaul/re-think #crossposting