Pentamatic 5.5cm f1.8 lens question...

You are probably both right. It might be a case where the battleship becomes a row boat because the bean counters got too much say. It's unfortunate, but it has and will likely continue to happen all too often. Growing companies that spend too much time on generating profits over products, often don't pay attention to long term goals and someone switches direction as a reaction to what happens, and many times it's not for the better. Someone might be great at balancing a budget, but are worthless as an engineer, or vice/versa.

The composition and thickness of sheet metal on the Model T that's still running (in it's original paint) in the 21st century versus my 1959 Chevy Impala's 4 foot long rusted seams at the hood and fender lines in 1972 that would flap in the breeze - or - the untarnished quality of 1950's stainless steel flatware over the flakey and pitted finishes on the minimum chromium alloy cheapos of the 1980's onward. Given enough time on the planet, we've all seen results like these, and I'd doubt that Yashica managed to get through 60+ years without it happening to them, and it certainly looks like the Pentamatic years had more than a couple of misteps in that direction that reek of burned and counted beans.

It's probably not possible to be certain if that's the case, since Yashica was a privately held Japanese company in and around the Showa era. Corporate culture of the time would dictate that any finacial faux pas wouldn't even be aknowledged out loud, let alone be publicy discussed beyond management's walls. The bigger the issue, the tighter the lips would be.

Just a guess, but the combination of buying (and paying for) Zunow and Nicca in the late 50's, maybe the development costs for lenses that obviously never materialised in the Pentamatic line, then ramping up design and production costs to get back into M42 territory with a whole new lineup... it all may have created a constantly squawking banker or accountant to finally cut, cut, cut until everything was bleeding in buckets.

More blades, more close to a perfect circle, so maybe it helps to better distribute the light incoming from a circular shaped lens, than with a hexagon or rhombus shape. My knowledge about optics is zero, but it seems that changing from 8 to 6 blades was not affecting much of the final results on the picture, in comparison with the benefits of simplifying the design, reducing parts and costs.