A couple of miscellaneous yet related comments to the discussion:
Although there is not a rule on WoF about getting the wheel all the way around during the main game, there was a rule when I was on the show that basically gave the host/producers the right to rule a spin invalid because it went almost nowhere; I assume that rule is still on the books.
Also, I teach a number theory course which contains a couple of units on cryptography, and yes, Mike, the distribution you show is somewhat of a standard one. Of course, all such distributions are based on a sampling of actual text; however large it may be, it's only an approximation of what the true distribution is. That's why the only part of the distribution that carries much significance is that of the high frequency letters. I tell my students that those stop with the S... that H, D, and L are on the border between high and medium frequency. And yes, the H is on the list because of its pairings with several letters, but primarily T, as TH occurs often, as does THE (not just as a word, but as a part of other words). The students generally enjoy finding out that Wheel of Fortune is "wrong." :-)
As it turns out, the cryptography course I took was not long before my appearance on the show, and had I made it to the bonus round, I would have chosen H instead of L (this was in 1986, when you picked your own five consonants and one vowel). But, 'twas not to happen.