MB playfields have 17 screens, 11 trapped and untrapped colors. The most of any machine I have heard of. Those areas of blue are shades of blue, and there are fonts (not text but a graphics term, google it) and gradients all over the playfield.
Not sure how many of you have done any complex high tech screen printing, but I have done some R&D work screening fighter cockpit nomenclature warning light blanks and making them night vision compatible. We had several stacked screen prints but not 17, and we were using single transparent ink colors, an ir blocker, and a black dead front overspray developed using a paint formula for stealth jet fighter radar absorbing paint. And we had trouble getting 3 layers down without rejects, not 17, but our problem was light leaks, and reflected sunlight not missing text, splotchy gradients due to dust and blocked screens, or smudged artwork due to dragging the squeegee too hard or fast. And then there are all the factors that affect the quality of the image like silk size, ink viscosity, humidity, air quality, curing times, oven curing, UV curing, room temp curing. It can be hard to figure out without an experienced operator giving you pointers. We had two old ladies that had been doing the non-technical interior airline lighting screen printing for years, which was our mainstay money maker. So all those fasten seatbelt signs and lavatory occupied signs. They knew how to sling ink, and it was their expertise that let us be more sucessful with our R&D work.
Hope that helps explain a little of the complexity of the MB screening process.