Do you know the size of your readers' windows?
How is the 93% calculated? Does it correct for multiple comparisons?
Given some outside knowledge, that these 6 choices are not unrelated, but come from a ordered space of choices, the result that one value is special and all the others produce identical results is implausible. I predict that it is a fluke.
Yes, I'm finding the result odd. I really did expect some sort of inverted V result where a medium sized max-width was "just right". Unfortunately, with...
If it's worth saying, but not worth its own post, even in Discussion, it goes here.