Bill...
Let's say you're right, and mediums are just cold readers. Let's also say that, as cold readers, they -know- that they need to overrepresent the most common letter guesses in their readings, but not make it obvious.
How to do that? Well, your counting method provides a perfect answer--use initials for common letters, but also use infrequent letters, just being sure to follow them with strings of names instead of initials only.
The point, Bill, is that your method wouldn't detect cold reading when a medium did this.
And its not just hypothetical (or zoological

) either. Or something that maybe a medium might become aware of only in the future (and why would we want to -assume- that knowing cold readers don't already understand this?

)
For example, Suzane Northrop guesses almost every letter of the alphabet in her readings which, to me, made her readings seem very much what I'd expect from a cold reader.
However, if she doesn't only mention all the letters, but actually strings many name guesses out for only infrequent letters...and only a few or none on the high frequency ones...she would not look like a cold reader at all, by your analysis.
I need to listen to my tape again, but its entirely possible that she -does- do this. If so, would you be satisfied with the result--and feel it is statistically sound--that your counting method makes JE look like a cold reader, but not Suzane?