I feel the same way. I think the difference across a range of pinhole sizes won't optimize an image to the point of making it succeed or not as an image worth looking at. Finding some discrete optimal pinhole size is an exercise in math and theory, not making significant photos, even if you can define precisely where along some spectrum your optimum image quality lies.

I also think there are many other, more interesting things about pinholes to explore, along with slit apertures, zone plates, and other lensless image forming methods. I recently acquired a handmade pinhole from bowzart that I'm hoping to have time to work with this weekend (if I can get out from under other chores and mount it), and the subject matter and other considerations are more important to me than whether it might be possible to get a 5% increase in 'sharpness' from a pinhole. One of those is the fun of using a tool expertly hand-made by a friend.

That being said, the OP does deserve some reasonable answers to his questions, and I think he's gotten that.

Lee