Do you have any sort of logical explanation or intuition about your stated result - that 75 percent of tests do not improve business results? It seems to sugge

Do you have any sort of logical explanation or intuition about your stated result - that 75 percent of tests do not improve business results? It seems to suggest that design just has to be good enough. Below some set threshold for visually appeal and/or usability the design hinders money-making. However, above that threshold, further improvement isn't necessary? If this is a reasonable interpretation, that is actually quite sad and suggests that all the new design-centered startups are wasting a lot of money.