I haven't heard anything, I think they're fairly evenly distributed. I tracked the McLeod ones. Here's what I got.
M - 16 different, all between 5 and 70
c - 7 different, all between 79 and 119
L - 17 different, all between 133 and 201
E - 11 different, all between 202 and 265
O - 28 different, all between 278 and 349
D - 12 different, all between 354 and 399
So with a little bit of guessing in between, I say
70 M, 62 c, 69 L, 64 E, 84 O, 50 D
Like I said, fairly even. The "c" might be a little shorter than I give it credit for, but there's at least 40 of them.
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Then, if we look at the Golds, with just a couple exceptions across the entire player run, they follow
R - 1
O - 2 to 6
K - 7 to 9
I - 10 to 12
E - 13 to 15
Making R the shortprinted letter.